arxiv:1308.2769v1 [astro-ph.ga] 13 aug 2013 · throughout this paper, we refer to the area inside...

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iv1

308

2769

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astr

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Corrected June 19 2013Preprint typeset using LATEX style emulateapj v 5211

H I ABSORPTION TOWARD H II REGIONS AT SMALL GALACTIC LONGITUDES

C Jones amp J M DickeySchool of Mathematics and Physics Private Bag 37 University of Tasmania Hobart 7001 Australia

J R DawsonSchool of Mathematics and Physics Private Bag 37 University of Tasmania Hobart 7001 Australia CSIRO Astronomy and Space

Science ATNF PO Box 76 Epping NSW 1710 Australia

N M McClure-GriffithsCSIRO Astronomy and Space Science ATNF PO Box 76 Epping NSW 1710 Australia

L D AndersonDepartment of Physics West Virginia University Morgantown WV 26506 USA

and

T M BaniaInstitute for Astrophysical Research Department of Astronomy Boston University 725 Commonwealth Ave Boston MA 02215 USA

Corrected June 19 2013

ABSTRACT

We make a comprehensive study of H I absorption toward H II regions located within |l| lt 10oStructures in the extreme inner Galaxy are traced using the longitude-velocity space distribution ofthis absorption We find significant H I absorption associated with the Near and Far 3kpc Arms theConnecting Arm Baniarsquos Clump 1 and the H I Tilted Disk We also constrain the line of sight distancesto H II regions by using H I absorption spectra together with the H II region velocities measured byradio recombination linesSubject headings galaxy structure HII regions

1 INTRODUCTION

The Extreme Inner Galaxy (EIG) has long been thesubject of intense astrophysical study as it provides ex-cellent opportunities to explore dynamics phenomena(from stellar to galactic scales) and physical environ-ments which do not exist in the large-scale Galactic diskThroughout this paper we refer to the area inside of

and including the 3kpc Arms as the EIG (ie RGal 4kpc) lsquoInner Galaxyrsquo is a term already used to describethe areas of the Milky Way inside the Solar Circle like-wise the term lsquoGalactic Centerrsquo (GC) usually refers tothe relatively small area with a Galactocentric radius lessthan a few hundred parsecsUseful reviews of the EIG environment include

Morris amp Serabyn (1996) and Blitz et al (1993) whodiscuss the interstellar medium (ISM) and structuralcomponents respectivelyRadio observations of the EIG region have been per-

formed since the 1950s (using the Dwingeloo 26 m an-tenna van Woerden et al 1957) These early studies dis-covered large-scale H I features with non-circular motions(Oort 1977) and concentrated on understanding theseindividual structures or particular objectsThe EIG has been extensively observed in CO Molecu-

lar tracers probe denser material than neutral hydrogen(H I) and CO is readily observed therefore CO obser-vations allow for analysis of regions in which the ISMis concentrated into structures such as arms and bars(Dame et al 2001) In contrast observations of atomicgas trace diffuse interstellar clouds

While H I in the EIG has been well studied at low res-olutions it is only recently that high-resolution H I datawhich cover the entire EIG region have become avail-able (ie ATCA H I Galactic Center Survey (HIGCS)McClure-Griffiths et al 2012) These high-resolution H I

data allow an analysis of the beginnings of the spiralarms the transition between orbits associated with thebar a comparison to high-resolution molecular observa-tions dynamical models and molecular transitions aswell as investigations into the association of H I with theGalactic wind (McClure-Griffiths et al 2012)As a result of the variation in the temperature of in-

terstellar hydrogen H I emission and absorption spectraprobe different phases of the ISM In most emission spec-tra it is the warmer components that dominate How-ever cool gas is readily observed in absorption againstbackground continuum sources where it may be disen-tangled from warmer material along the line of sightOne advantage to studying HI absorption in the EIG isthat it probes this predominantly cool material whichtends to be more localised in space and more closelyconfined to structural entities such as armsPrevious H I absorption studies have been vital to our

understanding of the structure rotation and the natureof atomic gas in the EIG region These include observa-tions of absorption features associated with non-circularvelocities Radio Arc non-thermal filaments as well asparticular objects including SgrA (Lang et al 2010 andreferences therein)While high-resolution H I absorption measurements

2

have been made towards several bright or otherwise in-teresting EIG continuum sources (Uchida et al 1992Roy 2003 Lang et al 2010 and references therein) acomplete H I absorption study of the EIG region hasnot been attempted This present H I absorption sur-vey constitutes the most complete study of H I absorptionagainst the continuum emission from the entire sample ofH II regions known with |l| lt 10o This study is only pos-sible due to recent H II region discovery surveys (whichprovide a list of target continuum regions with which tomeasure absorption against) and improved resolution inH I surveys that include the GC regionIn addition to providing a sample of bright continuum

sources against which to measure H I absorption H II

regions also provide an important secondary tracer ofGalactic structure the H II regions themselves Galac-tic H II regions are the formation sites of massive OBstars which have a main sequence lifetime of simtens ofmillions of years As a result Galactic H II regions revealthe locations of current massive star formation indicatethe present state of the ISM provide a unique probeof Galactic chemical evolution and are the archetypi-cal tracers of Galactic spiral structure (Anderson et al2011)In this work we measure HI absorption against only

those HII regions with known radio recombination line(RRL) velocities This sub-sample is discussed in Sec-tion 2 and the method of HI absorption is described inSection 3We then summarise the known EIG structures (Section

41) and their locations in Longitude-Velocity (lv) spaceWe plot these structures on an lsquolv crayon diagramrsquo anduse the diagram to consider the EIG lv distribution ofH I absorption in Section 5 and later for H II regions(Section 6)We combine the results from Sections 5 and 6 to ex-

plore the Galactic distribution of H II regions (Section 7)- through determining the lower limit of the line of sightdistance to each H II region based on its H I absorptionprofile and systemic velocityFinally a discussion of individual sources appears as

Appendix A

2 DATA amp SOURCE SELECTION

Large scale high resolution astronomical surveys arenow publicly available in many wavelength regimes Thiswork uses large-scale H I data and radio continuum maps

21 Radio Continuum

Radio continuum maps were sourced from theNRAO VLA Sky Survey (Condon et al 1998NVSS) and the Southern Galactic Plane Survey(McClure-Griffiths et al 2005 SGPS)The NVSS covers 82 of the sky (north of δ = minus40o)

at 14GHz resulting in 2326 4x4 degree continuum cubesof Stokes parameters and a catalog of continuum emis-sion sources Only the Stokes I maps were used for thiswork It should be noted that the NVSS maps do not in-clude zero spacing (uv) information and therefore manylarger diffuse emission regions particularly those in theLockman et al (1996) catalog are not detected

22 Neutral Hydrogen H I

For this work H I absorption spectra were extractedfrom the two SGPS datasets (5o lt |l| lt 10o) and theATCA H I Galactic Center Survey (5o lt |l| HIGCSMcClure-Griffiths et al 2012) Observations for theSGPS (I amp II) and ATCA HIGCS were performed withthe Australia Telescope Compact Array (ATCA) andsupplemented with data from the Parkes Radio Tele-scope The three surveys provide continuous coverageof the inner Galactic plane (253o lt l lt 20o) at sim2rsquo res-olution

23 Radio Recombination Lines

Catalogues of RRLs provide systemic velocities for H II

regions Large-scale surveys of RRLs from H II regionswere performed during the 1960rsquos to 1980rsquos More re-cently the Green Bank Telescope H II Region Discov-ery Survey (Anderson et al 2011 GBTHRDS) covered343o lt l lt 67o and detected RRLs from 448 new H II

regions effectively doubling the number known in thatlongitude range The GBTHRDS is complete to 180 mJyat 9 GHz and is able to detect all H II regions ionised bya single O-star to a distance of 12 kpcIn addition the GBTHRDS also includes a catalog of

known H II regions as of 2010 For the |l| lt 10o regionthis includes the combined works of Downes et al(1980) Wink et al (1982) Caswell amp Haynes (1987)Lockman (1989) Lockman et al (1996) and Sewilo et al(2004) The GBTHRDS team carefully compiled thisldquoknownrdquo catalog removing duplicate sources throughradio continuum and mid-infrared inspection Howeverthey note that it is ldquolikely to contain some residual con-tamination and duplicate entriesrdquo The combination ofthis ldquoknownrdquo catalog of H II regions and the GBTHRDSsource list within |l| lt 10o provided the sample list ofregions for this work Both the GBTHRDS catalog andthe compilation of previous catalogs can be found at[httpwwwcvnraoeduhrds]httpwwwcvnraoeduhrds

231 H II Regions Selected

There are nearly 200 known H II regions in the range|l| lt 10o |b| lt 15o with observed RRL velocities H I

absorption spectra were extracted towards a total of 151of these H II regions (see Figure Set 1) The remainingH II regions were either not visible in the NVSS contin-uum maps (also used by the GBTHRDS) usually diffuseH II regions from the Lockman et al (1996) catalog orH II regions with coordinates that could refer to severalcontinuum sources - see Table 1 Therefore this study ob-tains H I absorption spectra towards over 80 of knownH II regions with |l| lt 10o The lsquonamersquo for each H II re-gion is taken from the RRL catalog from which it wassourced

3 EXTRACTION OF THE H I ABSORPTIONSPECTRA

The hyperfine transition that creates the 21-cm H I lineis often seen in both emission and absorption from thesame region - indeed for most continuum sources a mix-ture of emission and absorption is observed Therefore amethod is required to separate the two

31 EmissionAbsorption Method

3

H II Region Reference Note

G351265+01019 GBTHRDS (2011) NVG351590+00183 Lockman (1989) MSG353035+00748 Lockman (1989) MSG353083+00358 Lockman (1989) MSG357998minus00159 Lockman (1989) DCG358319minus00414 Lockman et al (1996) NVG358623minus00066 Caswell amp Haynes (1987) DCG358661minus00575 Lockman et al (1996) NVG358664minus00575 Lockman et al (1996) NVG358974minus00021 Lockman et al (1996) NVG359186minus00026 Caswell amp Haynes (1987) DCG359730minus00407 Downes et al (1980) NVG359783+00040 GBTHRDS (2011) NVG359929+00045 GBTHRDS (2011) NVG000394minus00540 Downes et al (1980) NVG000521+00178 Lockman et al (1996) NVG000605+00325 Lockman et al (1996) NVG000656minus00058 Downes et al (1980) NVG000829+00193 Downes et al (1980) NVG001323+00086 Caswell amp Haynes (1987) DCG002303+00243 Lockman (1989) MSG005049+00254 Lockman (1989) NVG005332+00081 Lockman et al (1996) MSG006616minus00545 Lockman et al (1996) NVG006667minus00247 Lockman (1989) NVG006979minus00250 Lockman (1989) NVG007002minus00015 Lockman et al (1996) NVG007299minus00116 Lockman (1989) NVG007387+00668 Lockman (1989) NVG008415+00033 Lockman et al (1996) NVG008786minus00034 Lockman et al (1996) NVG009176+00032 Lockman et al (1996) DC

TABLE 1H II regions that were not included in this work Notes -

NV not visible at the SGPS pixel scale MS manycontinuum sources present at this location DC duplicate

(in both catalogs)

The emissionabsorption method (described in detailby Kolpak et al 2003) compares foreground cloud ab-sorption with continuum emission from a backgroundtarget Absorption eminusτ is derived by comparing thebrightness temperature as a function of velocity (v) bothon (Ton ) and off (ie the emission spectrum Toff) thecontinuum source Continuum maps were inspected withthe KARMA package (Gooch 1996) to ascertain the pixelpositions for lsquoonrsquo and lsquooffrsquo spectra to be extracted fromthe H I cubes one lsquoonrsquo and three lsquooffrsquo source positionswere chosen in accordance with the criteria identified inJones amp Dickey (2012)The simplest radiative transfer situation gives

Ton(v) = (Tbg + Tcont)eminusτ (v) + Ts(v)(1 minus eminusτ(v)) (1)

where Tcont is the continuum source brightness tempera-ture Ts is the spin temperature of the foreground cloudand Tbg represents any other background contributionAssuming that both the on and off spectra sample thesame gas subtraction of one from the other removes thecommon Ts(v)[1minuseminusτ (v)] and Tbg terms allowing opticaldepth to be measured directly The absorption is thengiven by

eminusτ =Ton minus Toff

Tcont

(2)

Fig 1mdash Figure Set H I emissionabsorption spectrum pairs Ineach figure the top panel shows the emission spectra The emissionis shown by the solid line (this is the average of the three lsquooffrsquo po-sitions see 31) and the emission envelope (difference between thelsquooffrsquo positions) is shown in grey Absorption eminusτ is displayed inthe bottom panel The H I absorption spectrum (see 2) is shown bythe solid line and the grey envelope signifies 3σ

eminusτ (calculated fromthe emission envelope see sect3) The absorption panel also displaysthe RRL velocities of the H II region (solid vertical lines) and thefluctuation in the baseline of the absorption spectrum (3σrms

eminusτ)

(horizontal dotted lines) The H II region name RRL velocity andreference are shown as well as the expected velocity ranges of EIGfeatures (see sect41) with the same color system as Figure 2

The quality of an absorption spectrum is not deter-mined by radiometer noise but rather the accuracy ofestimating the emission both on and around the back-ground continuum source As such we require absorp-tion to be significant in relation to both emission fluc-tuations and the noise in the baseline of the absorptionspectra (in a region without absorption features)For each absorption spectrum velocity channels with

significant absorption were selected for analysis Signifi-cant absorption is defined to satisfy both

bull significance at the 3σeminusτ level where σeminusτ is calcu-lated from the emission fluctuation envelope (thedifference in emission between lsquooffrsquo sources)

bull significance at the 3σrmseminusτ

level where σrmseminusτ

is the fluctuation in the baseline of the absorptionspectrum

The NVSS continuum maps are biased towards smallercontinuum temperatures (see sect21) as they do not includeall diffuse continuum emission However as Tcont actsas a scaling factor for eminusτ (see Equation 2) σeminusτ andσrms

eminusτwill also scale proportionately with any change

in continuum temperatureEmission and absorption spectrum pairs toward each

H II region appear in Figure Set 1

4 LONGITUDE-VELOCITY OVERVIEW OF THEEXTREME INNER GALAXY

Absorption spectra along lines of sight through theGalactic disk within the longitude range |l| lt 10o arecomplex and difficult to interpret This longitude re-gion includes structures associated with the GC and EIG

4

(RGal 4kpc) with highly non-circular motions as wellas features with velocities consistent with circular diskrotation (RGal amp 4kpc)Here we use the summary of EIG structures (sect41) to

construct an lsquolv crayon plotrsquo (Figure 2) marking promi-nent EIG features based on the integrated intensity of12CO in the same l b range (from Dame et al 2001)CO traces denser material than H I and therefore picks

out the densest features In the inner Galaxy atomicgas often acts to shield associated regions of moleculargas from photodissociation (Dickey amp Lockman 1990)Therefore H I absorption features may be identified withknown EIG molecular emission features using correla-tions in velocity structure (Lang et al 2010)As a result this plot provides a useful reference which

we use to consider the lv distribution of H I absorptionsect5 (and later H II region RRL velocities sect6)

41 Structures in the Extreme Inner Galaxy

Structures in the EIG include a long thin bar ashorter boxy-bulge bar the Near and Far 3 kpc armstilted H I inner disk or ring central molecular zone andthin twisted 100 pc ring (McClure-Griffiths et al 2012)In addition to these more prominent structures recentlv diagrams from H I and CO observations show manylsquoclumpyrsquo sub-structures not seen in previous EIG mod-els (Baba et al 2010)The angular extent of some of these EIG features is

quite large the Near 3kpc Arm is observed to l lt 348oand to surround all H I emission associated with the EIGregion a latitude range of at least |b| le 8o is required(Burton amp Liszt 1983) - well beyond the range of knownH II regions (|b| ltsim 2o)Many of these features are not often explicitly dis-

cussed in the literature and precise distances are usuallyunknown (Fux 1999) A summary of the EIG gas struc-tures many of which are visible in H I absorption spectraappears below Often these objects have several namesin the literature or several distinct features have beengiven the same name by different authorsFor a discussion of the evolution of the understand-

ing of H I and CO lv models in the EIG see Baba et al(2010) Burton amp Liszt (1983) provide a series of lv dia-grams with prominent features identified

411 Near and Far 3kpc Arms

Near 3kpc Armmdash The Near 3kpc Arm or Expanding3kpc Arm was discovered in the late 1950rsquos and is knownto lie in front of the GC (van Woerden et al 1957) How-ever it is not yet agreed whether the Near 3kpc Arm is alateral arm surrounding the bar or a small arm extendingfrom the end of the bar or an arm located where the barmeets its co-rotation radius (Rodrıguez-Fernandez 2011)Stretching over 35o in longitude the Near 3kpc Arm ex-ists at lsquoforbiddenrsquo velocities and its discovery provided vi-tal early support for a Galactic bar (Dame amp Thaddeus2008 and references therein) The Near 3kpc Arm ap-pears as the pink line in Figure 2

Far 3kpc Armmdash Despite the tendency for major anoma-lous velocity features in the GC to occur in positiveand negative velocity pairs (Burton amp Liszt 1983) it wasoriginally thought that there was no far side counterpart

Fig 2mdash Longitude-velocity ldquocrayonrdquo diagram for l lt |10o| b lt

|15|o Top panel - the lsquocrayonrsquo features overlaid on CO emissionmap (Dame et al 2001) Bottom panel - the lsquocrayonrsquo features (eachwith a velocity width of 20 km sminus1) The lsquocrayonrsquo color system is asfollows yellow - circular rotation allowed velocity envelope green- Connecting Arm purple - +135kmsminus1 Expanding Arm grey -Baniarsquos Clump 1 red - Tilted Disk cyan - Far 3kpc Arm yellow -velocities allowed by circular disk rotation pink - Near 3kpc Armblue - Looping Ridge While not explicitly labeled in the crayondiagram Baniarsquos Clump 2 can be seen as the thick vertical COfeature at l sim 3o 0 v 200 km sminus1 in the top panel (A colorversion of this figure is available in the online journal)

to the Near 3kpc Arm (Dame amp Thaddeus 2008 and ref-erences therin) Fux (1999) supposed the 135 km sminus1

Arm (discussed below) was the feature symmetric to theNear 3kpc Arm - however Fux also noted compositionaldifferences between the +135 km sminus1 and Near 3kpcArm attributing these to an asymmetric spiral struc-ture Dame amp Thaddeus (2008) reported the detection(in CO and then followed up in H I) of the far side coun-terpart to the Near 3kpc Arm named the Far 3kpc ArmThe Far 3kpc Arm appears as the cyan line in Figure 2

412 H I TiltedNuclear Disk

5

The H I inner tilted disk proposed by Liszt amp Burton(1980) was the result of a full 3D analysis of all knownH I emission in the inner kiloparsec of the Galaxy Itwas modeled by a series of closed elliptical gas orbitsThe disk is oriented at 237o with respect to the Galacticplane and accounts for positive velocity H I emission atb lt 0o l gt 0o and negative velocity gas at b gt 0o l lt 0o

(HIGCS) In Figure 2 the Tilted Disk appears as the redline crossing through (l v) = (0 0)

413 The Expanding Arm(s)

+135kmsminus1 Armmdash The location of the +135km sminus1

Arm or Expanding Arm is contentious throughout theliterature Fux (1999) assumes it is the far side coun-terpart to the Near 3kpc Arm (see sect411) Bania (1980)argues that the 3kpc and +135kmsminus1 Arms can not bedescribed together as a kinematic ring and Baba et al(2010) model the +135kmsminus1 Arm as part of the end ofthe bar on the far sideThe +135kmsminus1 Arm is more clumpy than the Near

3kpc Arm (Fux 1999) and extends nearly 30o in longi-tude and spans 3o in latitude near the GC (minus1o lt b lt 2o

at l = 359o) (Uchida et al 1992) Distance estimates forthe +135kmsminus1 Arm vary Simonson amp Madder (1973)and Bania (1980) give galactocentric radii only (34kpc and 28-35kpc respectively) whereas Uchida et al(1992) give a distance estimate of about 2kpc behind theGC (ie Dlos gt 10kpc)In Figure 2 the +135km sminus1 Expanding Arm appears

as the purple curve

Baniarsquos Clumpsmdash The individual emission clumps thatcomprise the +135kmsminus1 Arm probably either includeBaniarsquos Clumps 1 and 2 (Bania 1980 Bania et al 1986)or the two molecular cloud complexes are entering thedust lane shock (Liszt 2008) A detailed discussion ofthe H I properties of Baniarsquos Clump 2 can be found inMcClure-Griffiths et al (2012)Baniarsquos Clump 1 is seen as the grey line in Figure 2

whereas Baniarsquos Clump 2 is seen as the thick vertical COfeature at l asymp 3o sim 0 lt v ltsim 200 km sminus1 in the COemission map (top panel of Figure 2)

minus135km sminus1 Featuremdash Just as the Near 3kpc Arm hasa nearly symmetrical velocity and spatial counterpart aminus135km sminus1 Feature is thought to be located in the fore-ground of the GC but behind the Near 3kpc Arm asit is seen in OH absorption (Uchida et al 1992) Thisfeature is much less distinct than the +135km sminus1 Armindeed Bania (1980) did not detect it This feature is notincluded in Figure 2

414 Connecting Arm and Looping Ridge

Two features - the Connecting Arm and Looping Ridge- are visible in CO and H I emission as well as innear infrared dust extinction (Marshall et al (2008) andHIGCS) These features lead the bar major axis and arethe location of strong shearing shocks resulting in highvelocities (Fux 1999)The extent of both structures in l b v has been ex-

plored in detail by Marshall et al (2008) who use COdata to localise emission to specific lv structures

Connecting Arm - Positive Velocity Featuremdash The Con-necting Arm (at extreme positive velocities and lon-gitudes) was named as it seems to link the nuclearringdisk to the outer disk (Fux 1999) The Arm wassufficiently prominent in H I to be described as a distinctfeature in early EIG surveys (Liszt 2008) The locationof the Connecting Arm in front of or behind the GCwas originally unclear it has been interpreted as part ofthe central bar on the far side of the GC or as an artifactdue to velocity crowding along the line of sight but it isnow accepted to be a near side dust lane (Fux 1999 andreferences therein)The Connecting Arm appears as the green curve in

Figure 2

Looping Ridge - Negative Velocity Featuremdash The corre-sponding feature to the Connecting Arm (at negativevelocities and longitudes) is not always treated as a dis-tinct feature (Liszt 2008) and remains unnamed howeverMcClure-Griffiths et al (2012) refer to the negative fea-ture as the ldquoloopingrdquo ridge Liszt (2008) suggests thatthe Looping Ridge may be (temporarily) starved of gasand hence more difficult to detect and analyseIn Figure 2 the Looping Ridge appears as the blue

curve

5 LONGITUDE-VELOCITY DISTRIBUTION OF H I

ABSORPTION TOWARD THE EXTREMEINNER GALAXY

Figure 3 displays the H I absorption in lv spaceand compares this distribution with the EIG structures(sect41) H I and CO emissionTable 2 notes if significant H I absorption is associated

with any EIG feature for each H II regionIt is immediately obvious that the H I absorption dis-

tribution is not random but closely follows the identifiedEIG features This is not surprising as cold H I gas seenin absorption is a good tracer of Galactic structureH I absorption is associated with the allowed circular

rotation velocities (as expected) as well as the Near andFar 3kpc Arms Connecting Arm and Baniarsquos Clump 1

51 H I Absorption Associated with the 3kpc Arms

The CO emission from both the Near and Far 3kpcArms is contained within |b| lt 1o (Dame amp Thaddeus2008) similar to the Galactic latitude range of the H II

regions in this work (|b| 15o) Furthermore both 3kpcArms are thought to span |l| 13o which includes thewhole longitude range of this work Therefore if an H II

region is located behind either of the 3kpc Arms H I

absorption should be visible at velocities pertaining tothat armFigure 3 demonstrates that significant H I absorption

is seen toward the Near 3kpc Arm at all longitudes al-though there is a conspicuous gap in absorption at lon-gitudes sim 356 lt lo ltsim 358 consistent with a paucity ofH II regions for which to measure absorption towards In-deed 67 H II regions display absorption associated withthe Near 3kpc ArmThere is less absorption associated with the Far 3kpc

Arm than with the Near (sim 10 33) with the site ofgreatest absorption for the Far 3kpc Arm centered atl asymp 7o (see Figure 4) The disparity in the amount ofH I absorption may be an effect of the smaller latitude

6

Region N3 CA TD +E135 BC1 F3 Region N3 CA TD E135 BC1 F3

G350004+00438 N middot middot middot middot middot middot middot middot middot middot middot middot N G000284minus00478 Y middot middot middot N N middot middot middot N

G350129+00088 Y middot middot middot middot middot middot middot middot middot middot middot middot N G000361minus00780 Y middot middot middot N N middot middot middot Y

G350177+00017 N middot middot middot middot middot middot middot middot middot middot middot middot Y G000382+00017 Y middot middot middot N Y middot middot middot N

G350330+00157 Y middot middot middot middot middot middot middot middot middot middot middot middot Y G000510minus00051 Y middot middot middot N N middot middot middot N

G350335+00107 Y middot middot middot middot middot middot middot middot middot middot middot middot N G000572minus00628 Y middot middot middot N N middot middot middot N

G350524+00960 N middot middot middot middot middot middot middot middot middot middot middot middot N G000640+00623 Y middot middot middot Y N middot middot middot Y

G350769minus00075 N middot middot middot middot middot middot middot middot middot middot middot middot N G000729minus00123 Y middot middot middot N N middot middot middot Y

G350813minus00019 N middot middot middot middot middot middot middot middot middot middot middot middot Y G000838+00189 Y middot middot middot Y Y middot middot middot Y

G350996minus00557 N middot middot middot middot middot middot middot middot middot middot middot middot Y G001125minus00105 Y middot middot middot N Y middot middot middot Y

G351028+00155 Y middot middot middot middot middot middot middot middot middot middot middot middot Y G001149minus00062 Y middot middot middot Y N middot middot middot Y

G351047minus00322 N middot middot middot middot middot middot middot middot middot middot middot middot N G001324+00104 N middot middot middot N N middot middot middot N

G351192+00708 N middot middot middot middot middot middot middot middot middot middot middot middot N G001330+00088 Y middot middot middot N N middot middot middot Y

G351201+00483 N middot middot middot middot middot middot middot middot middot middot middot middot N G001488minus00199 Y middot middot middot N Y middot middot middot Y

G351358+00666 N middot middot middot middot middot middot middot middot middot middot middot middot Y G002009minus00680 Y N middot middot middot N middot middot middot N

G351359+01014 N middot middot middot middot middot middot middot middot middot middot middot middot N G002404+00068 N N middot middot middot N middot middot middot N

G351467minus00462 N middot middot middot middot middot middot middot middot middot middot middot middot N G002418minus00611 N N middot middot middot N middot middot middot N

G351601minus00348 N middot middot middot middot middot middot middot middot middot middot middot middot Y G002510minus00028 Y N middot middot middot Y middot middot middot N

G351662+00518 Y middot middot middot middot middot middot middot middot middot middot middot middot N G002611+00135 Y N middot middot middot N middot middot middot N

G351691+00669 N middot middot middot middot middot middot middot middot middot middot middot middot N G002819minus00132 N N middot middot middot N middot middot middot N

G352233minus00151 Y middot middot middot middot middot middot middot middot middot middot middot middot N G002901minus00006 Y N middot middot middot N middot middot middot N

G352313minus00440 Y middot middot middot middot middot middot middot middot middot middot middot middot Y G002961minus00053 Y N middot middot middot N middot middot middot Y

G352398minus00057 Y middot middot middot middot middot middot middot middot middot middot middot middot N G003270minus00101 Y N middot middot middot middot middot middot middot middot middot Y

G352521minus00144 Y middot middot middot middot middot middot middot middot middot middot middot middot N G003342minus00079 Y Y middot middot middot middot middot middot middot middot middot Y

G352610+00177 N middot middot middot middot middot middot middot middot middot middot middot middot N G003439minus00349 Y N middot middot middot middot middot middot middot middot middot N

G352611minus00172 Y middot middot middot middot middot middot middot middot middot middot middot middot N G003449minus00647 Y Y middot middot middot middot middot middot middot middot middot N

G352866minus00199 Y middot middot middot middot middot middot middot middot middot middot middot middot N G003655minus00111 Y N middot middot middot middot middot middot middot middot middot N

G353186+00887 N middot middot middot middot middot middot middot middot middot middot middot middot N G003928minus00116 Y N middot middot middot middot middot middot middot middot middot Y


G353381minus00114 Y middot middot middot middot middot middot middot middot middot middot middot middot N G004346+00115 N N middot middot middot middot middot middot middot middot middot N

G353398minus00391 N middot middot middot middot middot middot middot middot middot middot middot middot N G004412+00118 Y N middot middot middot middot middot middot middot middot middot Y

G353557minus00014 Y middot middot middot middot middot middot middot middot middot middot middot middot Y G004527minus00136 Y N middot middot middot middot middot middot middot middot middot Y


G354418+00036 N middot middot middot middot middot middot middot middot middot middot middot middot N G005193minus00284 Y Y middot middot middot middot middot middot middot middot middot N

G354486+00085 Y middot middot middot middot middot middot middot middot middot middot middot middot Y G005479minus00241 Y N middot middot middot middot middot middot middot middot middot Y

G354588+00007 Y middot middot middot middot middot middot middot middot middot N N G005524+00033 Y Y middot middot middot middot middot middot middot middot middot Y

G354610+00484 Y middot middot middot middot middot middot middot middot middot N Y G005633+00240 N Y middot middot middot middot middot middot middot middot middot N

G354664+00470 N middot middot middot middot middot middot middot middot middot N N G005899minus00427 N Y middot middot middot middot middot middot middot middot middot N

G354665+00247 N middot middot middot middot middot middot middot middot middot Y N G006014minus00364 Y N middot middot middot middot middot middot middot middot middot N

G354717+00293 N middot middot middot middot middot middot middot middot middot Y N G006083minus00117 Y N middot middot middot middot middot middot middot middot middot Y

G354934+00327 Y middot middot middot middot middot middot middot middot middot Y Y G006148minus00635 Y N middot middot middot middot middot middot middot middot middot N

G354979minus00528 N middot middot middot middot middot middot middot middot middot N N G006160minus00608 Y N middot middot middot middot middot middot middot middot middot N

G355242+00096 Y middot middot middot middot middot middot Y middot middot middot Y G006225minus00569 N Y middot middot middot middot middot middot middot middot middot N


G355532minus00100 Y middot middot middot middot middot middot Y middot middot middot N G006553minus00095 Y Y middot middot middot middot middot middot middot middot middot Y

G355581+00288 Y middot middot middot middot middot middot Y middot middot middot Y G006565minus00297 N Y middot middot middot middot middot middot middot middot middot Y

G355661+00382 Y middot middot middot middot middot middot Y middot middot middot N G007041+00176 Y N middot middot middot middot middot middot middot middot middot Y

G355696+00350 Y middot middot middot middot middot middot Y middot middot middot N G007176+00087 Y N middot middot middot middot middot middot middot middot middot N

G355700minus00100 Y middot middot middot middot middot middot N middot middot middot N G007254minus00073 Y N middot middot middot middot middot middot middot middot middot Y

G355734+00138 Y middot middot middot middot middot middot Y middot middot middot N G007266+00183 Y Y middot middot middot middot middot middot middot middot middot N

G355801minus00253 Y middot middot middot middot middot middot N middot middot middot N G007299minus00116 N N middot middot middot middot middot middot middot middot middot N

G356230+00066 Y middot middot middot middot middot middot N middot middot middot N G007420+00366 Y N middot middot middot middot middot middot middot middot middot Y

G356235+00642 Y middot middot middot middot middot middot Y middot middot middot N G007466minus00279 Y N middot middot middot middot middot middot middot middot middot N

G356307minus00210 Y middot middot middot middot middot middot N middot middot middot N G007472+00060 Y N middot middot middot middot middot middot middot middot middot Y

G356470minus00001 Y middot middot middot middot middot middot N middot middot middot Y G007700minus00079 N N middot middot middot middot middot middot middot middot middot N

G356560minus00086 Y middot middot middot middot middot middot N middot middot middot N G007768+00014 Y Y middot middot middot middot middot middot middot middot middot N

G356650+00129 Y middot middot middot middot middot middot Y middot middot middot N G007806minus00621 Y Y middot middot middot middot middot middot middot middot middot N

G357484minus00036 N middot middot middot middot middot middot N middot middot middot Y G008005minus00484 Y Y middot middot middot middot middot middot middot middot middot N

G357970minus00169 Y middot middot middot middot middot middot N middot middot middot N G008006minus00156 Y Y middot middot middot middot middot middot middot middot middot Y

G357998minus00159 Y middot middot middot middot middot middot N middot middot middot N G008094+00085 N N middot middot middot middot middot middot middot middot middot N

G358319minus00414 N middot middot middot middot middot middot N middot middot middot N G008103+00340 Y N middot middot middot middot middot middot middot middot middot N

G358379minus00840 N middot middot middot middot middot middot N middot middot middot N G008137+00228 N N middot middot middot middot middot middot middot middot middot N

G358530+00056 N middot middot middot N N middot middot middot N G008362minus00303 Y N middot middot middot middot middot middot middot middot middot N

G358552minus00025 N middot middot middot N N middot middot middot N G008373minus00352 Y Y middot middot middot middot middot middot middot middot middot N

G358616minus00076 Y middot middot middot N N middot middot middot N G008432minus00276 Y N middot middot middot middot middot middot middot middot middot Y

G358623minus00066 Y middot middot middot Y N middot middot middot N G008666minus00351 Y N middot middot middot middot middot middot middot middot middot N

G358633+00062 Y middot middot middot Y N middot middot middot N G008830minus00715 Y N middot middot middot middot middot middot middot middot middot N

G358652minus00078 N middot middot middot N N middot middot middot N G008865minus00323 Y N middot middot middot middot middot middot middot middot middot N

G358680minus00087 N middot middot middot Y N middot middot middot N G009178+00043 Y N middot middot middot middot middot middot middot middot middot N


G358720+00011 Y middot middot middot N N middot middot middot N G009682+00206 N N middot middot middot middot middot middot middot middot middot N

G358797+00058 Y middot middot middot N N middot middot middot N G009717minus00832 Y N middot middot middot middot middot middot middot middot middot N

G358827+00085 N middot middot middot N N middot middot middot N G009741+00842 Y N middot middot middot middot middot middot middot middot middot N

G359159minus00038 Y middot middot middot N N middot middot middot N G009875minus00749 Y Y middot middot middot middot middot middot middot middot middot N


G359432minus00086 Y middot middot middot N N middot middot middot N G009982minus00752 Y N middot middot middot middot middot middot middot middot middot N

G359467minus00172 Y middot middot middot N N middot middot middot Y middot middot middot middot middot middot middot middot middot middot middot middot middot middot middot middot middot middot middot middot middot

TABLE 2Presence of significant H I absorption in EIG features for each H II region EIG features are listed in line of sight orderN3= Near 3kpc Arm CA= Connecting Arm TD= H I Tilted Disk E135= +135km sminus1 Expanding Arm BC1= Baniarsquos Clump

1 F3= Far 3kpc Arm

7

Fig 3mdash lv diagrams showing velocity channels with signifi-cant absorption for each H II region overlaid onto top panel -the lsquocrayonrsquo plot of EIG features (see Figure 2) middle panel - H Iemission (the intensity map was created from the SGPS I amp II andATCA HIGCS) bottom panel - CO emission (see Figure 2) (Acolor version of this figure is available in the online journal)

extent of the Far 3kpc Arm which is particularly thin inthe fourth quadrant (Dame amp Thaddeus 2008)Both the HIGCS and Dame amp Thaddeus (2008) report

a bifurcation in the velocities Far 3kpc Arm (in lv space)at l lt 6o There is limited evidence of this bifurcation atlongitudes extending to asymp 7o the best example of this isin the absorption spectrum of G007176+00087 (see Fig-ure Set 1) The Near 3kpc Arm also displays evidence ofbifurcation in both the H I emission and absorption nearl = 358o (see for example G358616-00076 G358623-00066 G358633+00062 and G359432-00086 in FigureSet 1)

511 The Longitude-Velocity Location of the 3kpc Arms

The locus of each of the 3kpc Arms as tracedby H I absorption in lv space was also investigatedDame amp Thaddeus (2008) provide lv fits to the Near andFar 3kpc Arms and report a velocity dispersion of 21kmsminus1 for both Arms However they excluded large regionsof longitude within |l| lt 10o from the computation ofthe physical properties of each armIn order to investigate the locus of each Arm in lv

space a subset of absorption channels were selectedfor analysis (see Figure 4) We included all channelswithin 1o lt |l| lt 9o (between 9o lt |l| lt 10o thereis ambiguity between the 3kpc Arms and the circularrotation velocities and for |l| lt 1o there is ambigu-ity with the Tilted Disk) which had velocities outsidethe envelope of allowed circular-rotation velocities (ieVcircularminusrotation lt |V | lt 110km sminus1) and were not asso-ciated with either of Baniarsquos Clumps Linear fits to theseappear as Equations 3 and 4 for the Near and Far armsrespectivelyNear 3kpc Arm

VN3kpc = minus592+ 412lplusmn 867 (3)

VF3kpc = +577+402lplusmn 1561 (4)

In both cases the linear fits (plusmn5σ) of the struc-ture as given by H I absorption are consistent with theDame amp Thaddeus (2008) fits from CO emission (seeFigure 4)

Fig 4mdash Velocity channels of significant H I absorption thoseincluded in the tracing of the 3kpc Arms are shown in black whilethose channels which were excluded from the analysis are in greyThe fits of Dame amp Thaddeus (2008) are given by the grey bands(see Figure 2) the fits from this analysis are displayed in green(A color version of this figure is available in the online journal)

6 LONGITUDE-VELOCITY DISTRIBUTION OFH II REGIONS TOWARD THE EXTREME INNER

GALAXY

H II regions provide radio continuum sources to mea-sure H I absorption toward but they also provide a sec-ondary tracer of the EIG region - their own systemicvelocitiesThe lv distribution of known H II regions has previ-

ously been investigated by Anderson et al (2012) how-ever all H II regions with highly non-circular motions (ie

8

those of interest to this work) were excluded from theiranalysis The lv distribution of H II region RRL veloc-ity components used in this work is shown in Figure 5 -note for H II regions with multiple velocity componentsall are shownJust as the distribution of H I absorption was closely

associated with known lv features in the EIG region (sect5Figure 3) the systemic velocities of H II regions also tracethese structures

Fig 5mdash Longitude-velocity lsquocrayonrsquo diagram (see Figure 2)showing the distribution of H II region RRL velocity compo-nents(A color version of this figure is available in the online jour-nal)

The circular-rotation allowed velocities (yellow enve-lope in lsquocrayon plotsrsquo) account for sim 85 of the H II re-gion RRL velocity components Green et al (2011) in astudy of 67 GHz methanol masers near the EIG find thesame velocity range accounts for sim 79 of their sampleHowever only sim 10 of H II regions with a single RRLvelocity component are associated with EIG features Alist of H II regions with RRL velocities associated withan EIG structure appears in Table 3

61 H II Regions Associated with RGal 4

Until recently it was believed that there are no knownH II regions inside of the 3kpc Arms except in the TiltedDisk (Rodrıguez-Fernandez 2006) Green et al (2011)found no significant 67 GHz methanol maser emissiontowards the +135km sminus1 Expanding Arm nor the Con-necting Arm suggesting that the features are primar-ily gas that is not undergoing high-mass star formationThis is in-keeping with observations of other early-typebarred galaxies which show star formation in the centralnuclear region and at the ends of the bar but not inthe dust lanes along the bar (Rodriguez-Fernandez et al2006)Using the collated H II region catalog of Paladini et al

(2003) Rodriguez-Fernandez et al (2006) found no H II

regions associated with structures outside the NuclearDisk within |l| lt 2o The GBTHRDS recorded RRLvelocity components from 21 previously unknown H II

regions within |l| lt 2o many (especially in Quad-rant IV) with non-circular velocities - these H II re-gions are included in the target list of this work How-ever as the Rodriguez-Fernandez et al (2006) study

found these new H II regions are associated (in lv space)with the Nuclear Disk and Looping Ridge intersectionRodriguez-Fernandez et al (2006) then investigated awider longitude range but could not identify any dustlane associated H II regions It should be noted thatRodriguez-Fernandez et al (2006) did not rule out thepossibility of undetected ultra-compact H II regions inthe dust lanesOne diffuse H II region G007700-0079 identi-

fied by Lockman et al (1996) (but not includedin the Paladini et al (2003) catalog used in theRodriguez-Fernandez et al (2006) study) appears tohave one of its RRL velocity components associated withthe Connecting Arm There is also evidence of two67 GHz methanol masers tracers of current high-massstar formation in the same part of lv space (see Fig-ure 1 of Green et al 2011) In addition there are fourH II region RRL velocity components associated with the+135kmsminus1 Expanding Arm andor Baniarsquos Clump 1 (atl v =sim minus4osim 100 km sminus1) as well as two 67 GHzmethanol masers from the Methanol Multibeam survey(cited in Green et al 2011) however only two of these re-gions have single RRL velocity components (multi-RRLcomponent H II regions are probably the result of blend-ing multiple emission sources along the line of sight)Therefore there is evidence of some recent star forma-tion in these structuresThe other H II region of note is G002611+0135 as

it is the only H II region that distinctly lies outsidethe ldquocrayonrdquo lines that delineate EIG structures inFigure 3 Rodriguez-Fernandez et al (2006) suggestthat G002611+0135 could be associated with eithertheir structure rsquoJrsquo or Baniarsquos Clump 2 (see Figure 4 ofRodriguez-Fernandez et al 2006) The latitude of theH II region suggests a stronger association with Clump 2

62 H II Regions Associated with the 3kpc Arms

Only recently has there been evidence of significantstar formation (Green et al 2009) and large numbers ofH II regions (Bania et al 2010) in the 3kpc Arms Inemission frommolecular clouds the signatures of the 3kpcArms are clearly seen (Bania 1980) but the GBTHRDSwas unable to discover many new H II regions in either ofthe Arms However both arms demonstrate high-massstar formation as traced by about fifty 67 GHz methanolmasers (Green et al 2009)The certainty of associating H II regions with the 3kpc

Arms (in lv space) is best in the longitude range of thisstudy (|l| lt 10o) as outside this limit the expected veloc-ities of the 3kpc Arms overlap with circular-motion spiralarm models and the association becomes more ambigu-ous (Green et al 2009)Inside |l| lt 10o there are eleven H II region RRL veloc-

ity components consistent with the Near 3kpc Arm andtwo consistent with the Far 3kpc Arm This small num-ber of RRL components does not allow for a repetition ofthe analysis of sect511 using H II region RRL componentsrather than H I absorption

7 DISTANCE CONSTRAINTS FOR H II REGIONSFROM H I ABSORPTION

The analysis of an H I absorption spectrum towards aH II region can constrain the line of sight distance to theH II itself

9

Due to the lack of a reliable rotation model for the in-ner sim3kpc of the Milky Way kinematic distances to ob-jects near or in the EIG are the most difficult to ascer-tain However it should be possible to provide distanceconstraints for H II regions with allowed circular rotationsystemic velocities using H I absorption associated withEIG features as approximate distance indicatorsIn the Inner Galaxy inside the Solar Circle each ve-

locity corresponds to two degenerate solutions for thekinematic distance - each equidistant from the tangent(subcentral) point This kinematic distance ambiguitycan be resolved in cases where H I absorption is presentat the velocity of a known structure - which indicates theH II region must be located behind the absorbing gasThe distance arrangement of EIG features listed in

sect41 from the literature is assumed to be Near 3kpcArm Connecting Arm Tilted Disk Looping Ridge+135km sminus1 Expanding Arm (and Baniarsquos Clump 1)Far 3kpc Arm (however not all structures are expectedalong any single line of sight see Figure 2)Therefore if H I absorption is seen at velocities corre-

sponding to a particular feature the H II region must liein or beyond that structure In this way we use H I ab-sorption as an indicator of the lower limit of the line ofsight distance Dlos The RRL velocity of an H II regionalso hints at its location Table 3 lists those H II regionswith systemic velocities beyond the range expected bycircular rotation (see Figure 5) and associated with EIGfeature(s)A discussion of each H II region appears in Appendix

A

71 Kinematic Distances of Selected H II Regions

For H II regions with systemic velocities associated withnormal circular disk rotation (ie in the yellow envelopein Figure 5 RGal gt 4kpc) a Kinematic Distance Ambi-guity Resolution (KDAR) is attempted If a KDAR isachieved the kinematic distance to the H II region canthen be calculatedKDARs were achieved following these rules

bull if the H II region RRL is consistent with normalcircular disk rotation and not with any EIG fea-ture (see Table 3) (ie no kinematic distances arecalculated for regions with RGal lt 3kpc)

bull FAR If the H I absorption spectrum displays suffi-cient absorption associated with EIG features thenthe H II region must be located at the lsquofarrsquo kine-matic location - ie beyond the tangent point alongthe line of sight

ndash if |VRRL| lt 10km sminus1 a KDAR is attemptedonly if the H I absorption spectrum displaysabsorption associated with the Far 3kpc Armthis is imposed in order to avoid confusionwith EIG features at small velocities

ndash Quality lsquoArsquo far side KDARs were awarded toH II regions with statistically significant ab-sorption in EIG features including at least theNear and Far 3kpc Arms

ndash Quality lsquoBrsquo far side KDARs were awarded toH II regions with statistically significant ab-sorption in any EIG feature located on the farside of the GC

H II Region VRRL Ref Association

Single RRL Velocity Component H II Regions

G350996 minus 00557 +205 2 Far 3kpc ArmG351601 minus 00348 minus918 3 Near 3kpc ArmG352233 minus 00151 minus886 1 Near 3kpc ArmG352398 minus 00057 minus870 2 Near 3kpc ArmG352611 minus 00172 minus819 2 Near 3kpc ArmG354665 + 00247 +978 2 Baniarsquos Clump 1G354717 + 00293 +953 1 Baniarsquos Clump 1G355700 minus 00100 minus761 2 Near 3kpc ArmG356235 + 00642 +1163 2 +135km sminus1 ArmG358530 + 00056 minus2126 1 Looping RidgeG358552 minus 00025 minus2085 1 Looping RidgeG358616 minus 00076 minus2126 1 Looping RidgeG358623 minus 00066 minus2120 3 Looping RidgeG358652 minus 00078 minus2112 1 Looping RidgeG358680 minus 00087 minus2083 1 Looping RidgeG358694 minus 00075 minus2078 1 Looping RidgeG358720 + 00011 minus2061 1 Looping RidgeG358797 + 00058 minus2066 2 Looping RidgeG358827 + 00085 minus1933 1 Looping RidgeG359432 minus 00086 minus600 3 Near 3kpc ArmG359467 minus 00172 minus693 1 blended EIG features

G000510 minus 00051 +450 4 Far 3kpc ArmG003439 minus 00349 minus216 1 Near 3kpc ArmG007472 + 00060 minus178 2 Near 3kpc Arm

Multiple RRL Velocity Component H II Regions

G355532 minus 00100 a +38 1 middot middot middotG355532 minus 00100 b minus225 1 middot middot middotG355532 minus 00100 c minus826 1 Near 3kpc ArmG355532 minus 00100 d minus411 1 middot middot middotG355581 + 00028 a 1087 1 +135km sminus1 ArmG355581 + 00028 b minus761 1 Near 3kpc ArmG355581 + 00028 c 117 1 middot middot middotG355696 + 00350 a +30 1 middot middot middotG355696 + 00350 b minus791 1 Near 3kpc ArmG355734 + 00138 a +107 1 middot middot middotG355734 + 00138 b minus774 1 Near 3kpc ArmG359159 minus 00038 a minus1825 1 blended EIG features

G359159 minus 00038 b minus2156 1 blended EIG features

G000729 minus 00123 a +1053 1 Tilted DiskG000729 minus 00123 b +832 1 middot middot middotG006014 minus 00364 a +142 1 middot middot middotG006014 minus 00364 b minus319 1 Near 3kpc ArmG007700 minus 00079 a minus17 5 middot middot middotG007700 minus 00079 b +1517 5 Connecting Arm

TABLE 3H II Regions with an RRL velocity associated (in lv space)with known EIG structure(s) - see Figure 5 References

for VRRL are as follows 1 - GBTHRDS (2011) 2 -Lockman (1989) 3 - Caswell amp Haynes (1987) and 4 -

Downes et al (1980) 5 - Lockman et al (1996)

ndash Quality lsquoCrsquo far side KDARs were awarded toH II regions with large uncertainties (gt 50)in their calculated Dlos value (see sect711)

bull NEAR If the H I absorption spectrum displays noabsorption associated with any EIG features thenit must be located at the lsquonearrsquo kinematic loca-tion Here we assume that all the EIG featuresare visible within the latitude range of the targetH II regions (|b| lt 15o) Note that the linear scaleheights of the Near and Far 3kpc Arms is sim 103 pcFWHM (Dame amp Thaddeus 2008) assuming thatthe Far 3kpc Arm is at a uniform line of sight dis-tance of 115kpc this scale height corresponds to

10

a latitude range |b| 05o As a result if a H I

absorption spectrum towards an H II region locatedat |b| gt 05o displays no absorption associated withany EIG feature it is awarded a Near KDAR ofQuality rsquoCrsquo

ndash KDARs of Quality lsquoArsquo were given to all nearside H II regions unless

ndash the calculated Dlos value had large uncertain-ties (gt 50) then a Quality lsquoCrsquo KDAR wasgiven

bull No KDAR was attempted for H II regions with mul-tiple RRL velocity components as multiple sys-temic velocities suggest several ionisation sourcesalong the line of sight Note multi-RRL velocitycomponent H II regions account for less than 10of the H II regions within |l| lt 10o compared with30 for the Galactic plane in general (GBTHRDS)

H II regions with calculated kinematic distances arelisted in Table 4Four H II regions (G350177+00017

G350330+00157 G353557-00014 and G003949-00100) were deemed to lie at the far kinematic locationbeyond the EIG following the rules above Howeverthese four regions have RGal lt 3kpc ie they areoutside the bounds of the McClure-Griffiths amp Dickey(2007) rotation model and are therefore not included inTable 4If an H II region is awarded a far side KDAR based

on the above requirements a kinematic distance canbe calculated using a Galactic rotation curve model(which assumes circular rotation) The IAU Galac-tic Constants have been applied in these calculationsR0 = 85 kpc and Θ0 = 220km sminus1If an H II region must be located at least as far as the

subcentral point then its location inside or beyond theSolar circle is given by its systemic velocity In the InnerGalaxy velocities are positive in the first quadrant andnegative in the fourth The signs are reversed in theOuter Galaxy such that first quadrant sources locatedbeyond the Solar circle will have negative velocities andfourth quadrant sources in the Outer Galaxy will havepositive velocitiesThroughout this work the rotation curve of

McClure-Griffiths amp Dickey (2007) is used for regionswithin the Solar Circle In the outer Galaxy Dlos wascalculated using a flat rotation model ΘRGal

= Θ0

711 Kinematic Distance Uncertainties

We follow the distance uncertainty analysis methodof Anderson et al (2012) investigating the effects ofthe choice of rotation curve streaming motions andSolar rotation speed on kinematic distance calcula-tions We compare all sources of uncertainty tothe distances calculated from the rotation model ofMcClure-Griffiths amp Dickey (2007)Firstly we compute for a grid of (l v) posi-

tions the kinematic distance using the rotation curvesof McClure-Griffiths amp Dickey (2007) Brand amp Blitz(1993) and Clemens (1985) The standard deviationof these distances for each (l v) is then computed anddivided by the McClure-Griffiths amp Dickey (2007) dis-tance to obtain the percentage uncertainty due to choice

H II Region VRRL Ref Q RGal Dlos

KDAR Far - within rotation model boundaries

G350813 minus 00019 +03 3 B 86 169 plusmn42G351028 + 00155 +48 1 A 97 180 plusmn59G351358 + 00666 minus36 3 B 82 165 plusmn36G352313 minus 00440 minus134 1 A 59 143 plusmn26G354486 + 00085 +158 3 C 88 233 plusmnG354610 + 00484 minus234 1 A 39 123 plusmn22G354934 + 00327 +14 4 C 146 231 plusmnG355242 + 00096 +103 3 C 133 217 plusmnG355344 + 00145 +164 1 C 168 248 plusmnG000640 + 00623 +37 2 C 33 118 plusmnG000838 + 00189 +56 1 C 30 115 plusmnG003270 minus 00101 +49 3 C 63 147 plusmnG003342 minus 00079 +83 3 A 52 136 plusmn67G004412 + 00118 +41 3 C 71 156 plusmn89G004527 minus 00136 +102 1 A 54 138 plusmn39G005479 minus 00241 +214 3 A 41 125 plusmn23G005524 + 00033 +233 1 A 40 123 plusmn22G006083 minus 00117 +88 3 A 63 147 plusmn35G006553 minus 00095 +15 3 A 53 137 plusmn25G006565 minus 00297 +209 3 B 46 129 plusmn22G007041 + 00176 +89 1 A 66 149 plusmn31G007420 + 00366 minus123 1 C 122 206 plusmnG008006 minus 00156 +426 3 A 34 116 plusmn19G008432 minus 00276 +348 1 A 40 122 plusmn20KDAR Near

G351192 + 00708 minus34 3 C 82 03plusmnG353186 + 00887 minus47 3 C 76 09plusmnG359277 minus 00264 minus24 5 C 45 40plusmnG005889 minus 00427 +101 3 C 60 25plusmnG008137 + 00228 +206 3 C 51 35plusmn22G008666 minus 00351 +491 3 A 47 39plusmn14G008830 minus 00715 +266 1 C 47 39plusmn20

TABLE 4H II regions with calculated kinematic distances (in kpc)References for the RRL velocities are as follows 1)GBTHRDS (2011) 2) Lockman et al (1996) 3) Lockman

(1989) 4) Caswell amp Haynes (1987) 5) Wink et al (1982)Errors in kinematic distances marked with asterisks ()denote errors which are gt 100 note that while theseerrors are large the significance of the KDAR remains

of rotation curve We assessed a grid of |l| lt 10o and|v| lt 200km sminus1 with steps of 01 in each unitThis procedure is then repeated but instead of varying

the Galactic rotation model the percentage uncertaintydue to streaming motions (of 15km sminus1) and an alteredcircular Solar rotation speed of 255km sminus1 (Reid et al2009) are investigatedThe effect of these three sources of error are then added

in quadrature for each (l v) pair before transformationonto a face-on plot (Figure 6)It should be noted that kinematic distance errors at

small Galactic longitudes are intrinsically larger thanfor other sections of the Galaxy Equal steps in ve-locity map to unequal length steps in Dlos such thatdDlosdv prop sinminus1 l This can be seen in Figure 6 wherethe percentage uncertainty is higher for smaller longi-tudes

UNCERTAINTIES DUE TO ROTATION CURVE In ad-dition to larger uncertainties at small longitudes dueto the velocity gradient errors are also larger in theOuter Galaxy due to the uncertainty in the outer Galaxycircular rotation models Flat rising and falling ro-tation curves have been suggested for beyond the So-

11

Fig 6mdash Total percentage uncertainty in the line of sight distanceDlos caused by the choice of rotation curve non-circular streamingmotions of 15km sminus1 and by changing the Solar circular rotationspeed to Θo = 255km sminus1 Blank areas are indicative of |l| gt 10o

(where no error analysis was carried out) or percentage uncer-tainties gt 100 The EIG is shaded grey (no kinematic distanceswere calculated for this region) and the Solar Circle and Locus ofTangent Points appear as the black circles The percentage uncer-tainties are mirrored for lines of sight in the fourth quadrant hereonly l gt 0 is shown for clarity (A color version of this figure isavailable in the online journal)

lar circle Brand amp Blitz (1993) Honma et al (2007)Hachisuka et al (2009) Here we have used the ro-tation models of McClure-Griffiths amp Dickey (2007)Brand amp Blitz (1993) and Clemens (1985) Note thatthe McClure-Griffiths amp Dickey (2007) model has an ap-plicable Galactocentric range of 3 le RGal le 8 kpc As aresult the model was extrapolated to the Solar circle anda flat rotation curve was assumed for RGal gt Ro Thelargest discrepancy between these three models occurs atRGal sim 10 kpc but even at RGal lt Ro the models differsignificantly

UNCERTAINTIES DUE TO NON-CIRCULAR STREAM-ING MOTIONS Large non-circular motions have pre-cluded Galactic astronomers from fitting a rotation curveto the EIG Smaller-scale non-circular motions are ubiq-uitous in the Galaxy and are the result of system-atic velocity fields within a source or ordered large-scale Galactic streaming motions Anderson et al (2012)Bania amp Lockman (1984) suggest an uncertainty dueto non-circular motions of 5 to 10km sminus1 whereasKolpak et al (2003) assign an estimate of cloud-clouddispersion of 5 km sminus1 in addition to contributionsfrom Galactic scale streaming motions of 10 km sminus1Dickey et al (2003) and Jones amp Dickey (2012) find H I

absorption components extending to 10-20 km sminus1 be-yond the systemic velocity of H II regionsIn order to promote a conservative approach to kine-

matic distance uncertainties the random uncertainty dueto non-circular motions is set to 15 km sminus1 The contri-bution of errors due to streaming motions in relation tothe total uncertainty in kinematic distance is high espe-cially for small longitudes The errors due to non-circularmotions are the standard deviation of the three (l v)grids(l v) (l v+15) (l vminus15) divided by the (l v) dis-

tance all computed with the McClure-Griffiths amp Dickey(2007) rotation model

UNCERTAINTIES DUE TO SOLAR ROTATION PARAM-ETERS The IAU values for Ro = 85 kpc and Θo =220km sminus1 have been used throughout this work How-ever here we investigate the significance of an al-tered Solar rotation speed as suggested by Reid et al(2009) Two (l v) grids were computed with the rota-tion model of McClure-Griffiths amp Dickey (2007) usingΘo = 220 250km sminus1 The standard deviation of thesetwo grids at each locus was then divided by the stan-dard (ie Θo = 220km sminus1) distance to compute thepercentage uncertainty due to choice of Solar rotationparameters Note that the Reid et al (2009) value forRo = 84plusmn 06 kpc is consistent with the IAU value andis therefore not investigated here

72 Galactic Distribution of H II Regions

In order to examine the large-scale structure of theGalaxy H II regions with successfully calculated kine-matic distances were transformed into a face-on mapof the Milky Way (left panel of Figure 7) and also su-perimposed onto an artistrsquos conception of the Galaxy(right panel) The background image used in the rightpanel of Figure 7 was created using stellar H I andCO data (Churchwell et al 2009) and was reviewed inUrquhart et al (2012)In addition the kinematic distances from

Jones amp Dickey (2012) are also displayed Figure 7demonstrates the need for H II region discovery andKDAR studies for Galactic longitudes 340o lt l lt 350o

in order to further investigate the end of the bar anddifferentiate the Norma and Near 3kpc Arms as well asthe Sagittarius and Perseus Arms on the far side of thelocus of subcentral points (smaller circle in Figure 7)At the end of the bar in the first quadrant H II regionKDARs have been made by Anderson amp Bania (2009)and Bania et al (2012) - further encouragement for afourth quadrant studyRecently Dame amp Thaddeus (2011) identified an ex-

tension of the Scutum-Centaurus Arm at extreme dis-tances from the Sun in the first Galactic quadrant How-ever confirmation of this discovery requires tracing theArm over its entire longitude range Dame amp Thaddeus(2011) comment that molecular gas which constitutes thesection of Scutum-Centaurus Arm behind the Galacticcenter will be the most difficult to deconvolve In the lon-gitude range of this paper H II regions with systemic ve-locities opposite in sign to circular-disk rotation must belocated in the EIG or beyond the Solar circle Using H I

absorption features to resolve this ambiguity has allowedfor seven H II regions to be unequivocally placed in theouter Galaxy Several of these outer Galaxy regions (seeFigure 7) appear to trace the Scutum-Centaurus arm

8 SUMMARY

The EIG remains a difficult section of the Milky Way tostudy In terms of Galactic structure kinematic studiesin this region are hampered by a lack of rotation modelfor RGal lt 4kpc (and for the outer Galaxy) In additionthere remains a lack of consensus regarding the numberlocations and nomenclature of large-scale structures nearthe Galactic Centre (these are discussed in Section 41)

12

Fig 7mdash Positions of the H II region complexes for which a kinematic distance was calculated (Quality A B and C shown as green orangeand red markers respectively) Also shown are the Solar Circle and locus of tangent points (black circles) and kinematic distances for H IIregions from Jones amp Dickey (2012) (black markers) Error bars are calculated according to the analysis of sect711 the large uncertaintiesare not shown for quality C distances Background image credit [right panel] Hurt amp Benjamin in Churchwell et al (2009) (A colorversion of this figure is available in the online journal)

13

Despite this H I absorption associated with EIG featureswas successfully used as a distance indicator allowing forconstraints on the line of sight distance for over 80 ofthe sample of H II regions investigated or over 60 of allknown H II regions with systemic velocities in |l| lt 10oOver 67 of the H II regions demonstrate H I absorp-

tion associated with the Near 3kpc Arm (see Table 2)and therefore must be located at line of sight distancesof at least sim 5kpc A further 16 H II regions show absorp-tion associated with EIG features assumed to lie furtheralong the line of sight than the Near 3kpc Arm there-fore over 78 of the sample H II regions are locatedat Dlos amp 5kpc This is in keeping with the work ofLang et al (2010) who find sim 90 of their sample of 40EIG continuum sources must be located at least as faras the Near 3kpc ArmOf the 151 H II regions investigated 54 H II regions

display absorption from EIG features assumed to be onthe far side of the GC (the +135km sminus1 Expanding ArmBaniarsquos Clump 1 or Far 3kpc Arm) Consequently theseH II regions must be located at Dlos amp 85kpcAfter successfully resolving the nearfar kinematic dis-

tance ambiguity line of sight distances were calculatedfor 31 H II regions These distances suggest locationsfor the H II regions in known Galactic structures in-cluding the Norma Sagittarius and Perseus spiral Arms(see Figure 7) The 7 H II regions beyond the So-lar Circle are among the most distant Galactic H II re-gions known to exist and could be crucial to tracingthe Scutum-Centaurus Arm where identification of starformation with molecular tracers is extremely difficult(Dame amp Thaddeus 2011) Errors on these line of sightdistances are often large - due to the uncertainty of non-circular streaming motions and differences in Galacticrotation models - but the nearfar KDAR remains bothvalid and significantUsing a summary of EIG structures and the known lv

distribution of CO we construct a lsquocrayon diagramrsquo withwhich to investigate the distribution of H I absorption inthe EIG (Figure 2 Section 4) In Section 5 we find coldH I clouds signified by H I absorption associated withthe Near 3kpc Arm Connecting Arm Baniarsquos Clump1 Tilted Disk and Far 3kpc Arm There was minimalH I absorption associated with either the Looping Ridgeor the +135km sminus1 Expanding Arm The large amountof H I absorption associated with each of the 3kpc Armspresented an opportunity to fit a model to the lv locus ofeach Arm (sect51) We find a linear fit (in lv space) that isconsistent with the findings of Dame amp Thaddeus (2008)who used CO to trace the ArmsThe lv distribution of the RRL velocities of the 151

H II regions was investigated in Section 6 Like the H I

absorption distribution the systemic velocities of the H II

regions trace Galactic structures including spiral armsfeatures located near the Galactic center and possiblythe end of the bar While most H II regions posses RRLvelocity components allowed by circular Galactic rota-tion (suggestive of a location outside the EIG) smallernumbers of H II regions are found to be associated withthe H I Tilted Disk Near 3kpc Arm +135km sminus1 Ex-panding Arm Baniarsquos Clump 1 Connecting Arm andFar 3kpc Arm Using the RRL velocity and H I absorp-tion spectrum of each H II region we were also able toconstrain the Dlos for a further sample of H II regions

using only EIG features as a distance indicator

This research has made use of NASArsquos AstrophysicsData System the NASAIPAC Extragalactic Database(NED) and the SIMBAD database

14

APPENDIX

DISCUSSION OF INDIVIDUAL H II REGIONS

G350004+00438

The H I absorption spectrum does not give a clear indi-cation of any absorption associated with any EIG featureAt this longitude the velocity range of the Far 3kpc Armis not clearly distinct from velocities expected by normalcircular rotation

G350129+00088

The H I absorption spectra clearly demonstrates ab-sorption either side of the velocities expected by an as-sociation with the Near 3kpc Arm Quireza et al (2006)place the H II region at a line of sight distance of 62 kpc(ie on the near side of the GC)

G350177+00017

Evidence of absorption in the Far 3kpc Arms suggestsa far KDAR As with G350330+00157 (below) the cal-culated RGal and Dlos for the region are outside thebounds of the McClure-Griffiths amp Dickey (2007) rota-tion model

G350330+00157

While the H I absorption spectrum suffers from emis-sion fluctuations around the RRL velocity (sim minus60kmsminus1) there is evidence of absorption associated with theNear 3kpc Arm Assuming a far side KDAR the cal-culated RGal and Dlos are outside the bounds of theMcClure-Griffiths amp Dickey (2007) rotation model

G350335+00107

Evidence of H I absorption is seen either side ofthe velocities associated with the Near 3kpc Arm (seeG350129+00088 above) and is therefore located atleast as far as the Near 3kpc Arm along the line of sight

G350524+00960

G350524+00960 does not demonstrate any H I ab-sorption outside the velocities expected by normal circu-lar rotation If the near kinematic distance is thereforeassumed the H II region has a calculated Dlos asymp 19kpc

G350769-00075

The H I absorption spectrum of G350769-00075 doesnot give conclusive evidence for either a near nor farKDAR

G350813-00019

As the H I absorption spectrum of G350813-00019demonstrates absorption in velocities associated with theFar 3kpc Arm the H II region must be on the far side ofthe GC The positive (small) RRL velocity then locatesthe H II region at a line of sight distance beyond (butclose to) the Solar Circle

G350996-00557

Strong absorption is seen in the Far 3kpc Arm butnot in the Near 3kpc Arm The RRL velocity suggests alocation within the Far 3kpc Arm

G351028+00155

The H I absorption spectrum of G351028+00155demonstrates significant absorption at velocities corre-sponding to both the Near and Far 3kpc Arms and there-fore must be located at least as far as the Far 3kpc Armalong the line of sight The positive RRL velocity thenrequires that G351028+00155 is located in the outerGalaxy

G351047-00322


G351192+00708

H I absorption is evident in circular rotation allowedvelocities only If the near kinematic distance is thereforeassumed the H II region has a calculated Dlos asymp 03kpcMoises et al (2011) assumes the near kinematic distancehowever Quireza et al (2006) place the H II region at aline of sight distance of 171 kpc

G351201+00483

The H I absorption spectrum of G351201+00483 doesnot give conclusive evidence for either a near nor farKDAR Quireza et al (2006) place the object at 14 kpcat the near kinematic location

G351358+00666

Quireza et al (2006) assumes a near KDAR forG351358+00666 but H I absorption associated with ve-locities expected of the Far 3kpc Arm suggest that theH II region is located at the far kinematic location

G351359+01014

The H I absorption spectrum of G351359+01014 doesnot give conclusive evidence for either a near nor farKDAR

G351467-00462

Quireza et al (2006) give G351467-00462 a near sideKDAR but the H I absorption spectrum from this paperdoes not give conclusive evidence for a KDAR

G351601-00348

The RRL velocity for this H II region (-918 km sminus1Lockman (1989)) is associated with the Near 3kpc ArmGreen amp McClure-Griffiths (2011) also position a nearby67 GHz maser (l b = 351581minus0353)in the Near 3kpcarm

G351662+00518

G351662+00518 has a near zero RRL velocity (-29kmsminus1 Lockman (1989)) which is associated with locationsinside the EIG region near the Solar Cirle or at a verysmall line of sight distance from the Sun Absorptionat velocities associated with the Near 3kpc Arm implya Dlos gt 5kpc As there is no H I absorption associatedwith other EIG features (only the Far 3kpc Arm is ex-pected at this longitude) a location within RGal 3kpcis assumed

15

G351691+00669

No H I absorption falls outside the circular rotationenvelope of allowed velocities suggesting a near KDARHowever the positive RRL velocity suggests a locationin either the EIG or outer Galaxy

G352233-00151

This H II region has an RRL velocity associated withthe Near 3kpc Arm (-886km sminus1 GBTHRDS) Strongabsorption in the allowed circular rotation velocities andat velocities associated with the Near 3kpc Arm reaffirmthe location in the Arm

G352313-00440

Evidence of H I absorption in both the Near and Far3kpc Arms suggests a far side KDAR for G351313-00440

G352398-00057

Absorption is seen at the expected velocities of theNear 3kpc Arm which is also where the RRL velocityfor this H II region lies (-87km sminus1 Lockman (1989))Absorption up to 25 km sminus1 beyond the RRL velocityof an H II region is not uncommon (Dickey et al 2003Jones amp Dickey 2012) therefore it is assumed that theH II region is located in the Near 3kpc Arm

G352521-00144

Two RRL velocities have been recorded for G352521-00144 (-573 and -38 km sminus1 GBTHRDS) suggestive ofmultiple emission sources along the line of sight

G352610+00177

The H I absorption spectrum for G352610+00177 suf-fers from emission fluctuations As a result the poorquality spectrum does not give conclusive evidence for aKDAR

G352611-00172

G352611-00172 displays strong absorption at sim100km sminus1 approximately 20km sminus1 beyond the knownRRL velocity of the H II region (-819km sminus1 Lockman(1989)) As with G352398-00057 (above) G352611-00172 is assumed to lie in the Near 3kpc Arm Thislocation in the Near 3kpc Arm is approximately thesame as the line of sight distance given by Quireza et al(2006) (67 kpc)

G352866-00199

Evidence of absorption at velocities correspondingto the Near 3kpc Arm suggest a Dlos ge 5kpcGreen amp McClure-Griffiths (2011) position a nearby 67GHz methanol maser (l b = 352855minus0201) at the farkinematic location (Dlos asymp 11kpc)

G353186+00887

H I absorption is evident in circular rotation allowedvelocities only G353186+00887 If the near kinematiclocation is then assumed the H II region has a calculatedDlos asymp 09kpc Quireza et al (2006) provide a near sideKDAR for this H II region

G353218-00249

Also the source of a variable maser (Caswell et al2010) G353218-00249 has a small RRL velocity (-83km sminus1 GBTHRDS) and absorption present at Near3kpc Arm but not Far 3kpc Arm velocities Theseare evidence for a location near the EIG and as suchDlos ge 5kpc Rgal lt 3kpc is assumed

G353381-00114

The H I absorption spectrum of G353381-00114 dis-plays strong H I absorption associated with the Near 3kpcArm suggesting that the H II region must lie behind thefeature

G353398-00391

H I absorption is evident in circular rotation allowed ve-locities only if therefore a near side KDAR is assumedthe calculated Dlos asymp 52kpc

G353557-00014

H I absorption is present at velocities correspondingto both 3kpc Arms suggestive of a far side KDARHowever like the H II regions G350330+00157 andG350177+00017 the calculated RGal and Dlos fall out-side the boundaries of the McClure-Griffiths amp Dickey(2007) rotation model

G354200-00050

Strong absorption is centered at velocities tothe negative side of those expected for the Near3kpc Arm (see G352611-00172 and G352398-0057above)Green amp McClure-Griffiths (2011) were unable todetermine a KDAR for a nearby 67 GHz methanol maser(l b = 354206minus0038) Due to the H I absorption asso-ciated with the Near 3kpc Arm Dlos ge 5kpc is assumed

G354418+0036


G354486+00085

Caswell et al (2010) places a nearby 67 GHz methanolmaser (l b = 354496 0083) in the Far 3kpc Arm TheRRL velocity of the H II region (158km sminus1 Lockman(1989)) is slightly smaller than that expected for the Far3kpc Arm but the absorption indicates the H II regionmust be located at least as far along the line of sight asthe feature Due to the positive RRL velocity we assumethat G354486+00085 is located beyond the Solar Circle(see Table 4)

G354588+00007

A line of sight along the longitude of 354588o intersectsthe Near and Far 3kpc Arms as well as the assumed posi-tion of Baniarsquos Clump 1 The H I absorption spectrum ofG354588+00007 does not give conclusive evidence foreither a near nor far KDAR but absorption associatedwith the Near 3kpc Arm suggests Dlos ge 5kpc

16

G354610+00484

Significant H I absorption is present before and afterthe velocities expected of the Near 3kpc Arm as wellas at Far 3kpc Arm velocities A known strong 67GHz methanol maser is also in the region (Caswell et al2010) with a velocity equivalent to the RRL velocity(maser velocity -23km sminus1 RRL velocity -234km sminus1

(GBTHRDS)) Green amp McClure-Griffiths (2011) sug-gest a poor quality near side KDAR for the associatedmaser but a far kinematic distance is assumed here

G354664+00470

H I absorption is evident in circular rotation allowedvelocities only assuming a near side KDAR the calcu-lated Dlos asymp 45kpc

G354665+00247

No absorption is seen at the RRL velocity of the H II

region (978km sminus1 Lockman (1989)) nor at velocitiescorresponding to the Near 3kpc Arm However signif-icant absorption is seen at sim 70km sminus1 possibly asso-ciated with Baniarsquos Clump 1 No KDAR is given herehowever the high RRL velocity is suggestive of a locationin the EIG (Caswell et al 2010)

G354717+00293

As with G354665+00247 the high RRL velocity ofG354717+00293 suggests a location in the EIG The H I

absorption spectrum suffers from emission fluctuationsat the RRL velocity (953km sminus1 GBTHRDS) and noabsorption is present at Near 3kpc Arm velocities Atleast two masers with high velocities (sim 100km sminus1) areknown to exist in the area (Caswell et al 2010)

G354934+00327

G354934+00327 shares a similar absorption profileto that of G354717+00293 and G354665+00247 how-ever it does not share a highly non-circular RRL veloc-ity (14km sminus1 Caswell amp Haynes (1987)) Absorptionvelocities corresponding to all expected EIG features re-quires the H II region to be located at least as far alongthe line of sight as the Far 3kpc Arm Due to the positiveRRL velocity the H II region must then be located in theouter Galaxy beyond the Solar circle along the line ofsight

G354979-00528


G355242+00096

H I absorption is present at velocities corresponding tothe Near 3kpc Arm on the near side of the GC and thereis evidence of absorption on the far side of the GC dueto the Far 3kpc Arm and +135km sminus1 Expanding ArmA far side KDAR is given but due to the positive RRLvelocity the H II region must be located beyond the SolarCircle

G355344+00145

Absorption at the Near 3kpc Arm +135km sminus1

Expanding Arm and Far 3kpc Arm infer that the

H II region is located beyond the EIG along theline of sight The positive RRL velocity thenplaces the H II region beyond the Solar circleThere are several masers in the region which areassumed to lie within 3 kpc of the GC (see (l b) =(355343+0148) (355344+0147) and (355346+0149)in Green amp McClure-Griffiths 2011)

G355532-00100

This region has four known RRL velocities (38 -225-806 and -411 km sminus1 GBTHRDS) a strong indicationthat there are several emission sources along the line ofsight Note that the RRL velocity minus806km sminus1 is as-sociated with velocities expected of the Near 3kpc ArmNo KDAR is given

G355581+00288

Three RRL velocities are known towards the H II region(+1087 -761 and +117 km sminus1 GBTHRDS) As withG355532-00100 (above) this is an indication of severalsources along the line of sight No KDAR is given how-ever the RRL velocity minus761km sminus1 is associated withthe Near 3kpc Arm and the RRL velocity component+1087km sminus1 is associated with the +135km sminus1 Ex-panding Arm

G355611+00382

The near zero RRL velocity (-26 km sminus1 GBTHRDS)is indicative of a EIG location or a location near theSolar circle (either very close or at a great distancefrom the Sun) Absorption in velocities associated withthe Near 3kpc Arm and +135km sminus1 Expanding Armbut not at velocities corresponding to far side EIG fea-tures prompts Dlos ge 85kpc Rgal lt 3 kpc to begiven as a distance limit for the H II region In con-trast Green amp McClure-Griffiths (2011) presents a farside KDAR for a 67 GHz methanol maser at l b =355666+0398 which has a systemic velocity of sim minus2kmsminus1

G355696+0350

Two RRL velocities (3 and -791 km sminus1 GBTHRDS)suggest multiple emission sources along the line of sightat least one of which is associated with the Near 3kpcArm (-791km sminus1 RRL association) At this longitudethe velocities of the Near 3kpc Arm and the LoopingRidge (on the far side of the GC) overlap No KDAR isgiven

G355700-00100

G355700-00100 has an absorption profile and RRLvelocity (-761 km sminus1 Lockman (1989)) suggestive of alocation within the Near 3kpc Arm or Looping Ridge (asthe expected velocities of these features overlap at thislongitude) No KDAR is given

G355734+0138

There are multiple RRL velocities associated withG355734+0138 (107 and -774 km sminus1 GBTHRDS)No KDAR is given but the RRL velocity component atminus774km sminus1 is associated with the velocities expectedof the Near 3kpc Arm or Looping Ridge

17

G355801-00253

The velocity ranges of the Near 3kpc Arm and LoopingRidge continue to overlap at this longitude Two RRLvelocities are known (-315 31 km sminus1 GBTHRDS)suggestive of multiple sources along the line of sight NoKDAR is given

G356230+00066

At this longitude the expected velocities of theNear 3kpc Arm and Looping Ridge are distinct (seeabove) However the H I absorption spectrum ofG356230+00066 does not give conclusive evidence foreither a near nor far KDAR

G356235+00642

Absorption is seen at velocities corresponding to theNear 3kpc Arm and Looping Ridge It is assumed thatthe H II region is located in the +135km sminus1 ExpandingArm (due to the RRL velocity (1163km sminus1 Lockman(1989)) This is supported by absorption at velocitiescorresponding to the Looping Ridge (on the far side ofthe GC but closer to the GC than the +135km sminus1 Ex-panding Arm)

G356307-00210

A near zero RRL velocity (-4km sminus1 Lockman (1989))and absorption concurrent with Near 3kpc Arm velocitiessuggests Rgal lt 3 kpc for this H II region

G356470-0001


G356560-00086


G356650+00129

H I absorption is present in velocities corresponding tothe Near 3kpc Arm As such Dlos gt 5kpc is assumed

G357484-00036

The H I absorption spectrum suffers from emission fluc-tuations in the velocity ranges associated with the Near3kpc Arm and Looping Ridge As such the poor qualityspectrum does not allow a KDAR to be given for thisH II region

G357970-00169

The H I absorption spectrum of G357970-00169 dis-plays absorption at velocities associated with the Near3kpc Arm As a result Dlos gt 5kpc is assumed Thesmall RRL velocity and lack of absorption correspond-ing to other EIG features suggests a further constraintRGal lt 3kpc

G357998-00159

The H I absorption spectrum of G357998-00159 dis-plays absorption at velocities associated with the Near

3kpc Arm As a result Dlos gt 5kpc is assumed Thesmall RRL velocity and lack of absorption correspond-ing to other EIG features suggests a further constraintRGal lt 3kpc

G358319-00414


G358379-00840


G358530+00056

This H II region has an RRL associated with the Loop-ing Ridge or Tilted Disk(-2085km sminus1 GBTHRDS)however the spectrum is of poor quality and no absorp-tion is seen at velocities pertaining to any EIG feature

G358552-00025

This H II region has an RRL associated with the Loop-ing Ridge or Tilted Disk(-2085km sminus1 GBTHRDS)however the spectrum is of poor quality and no absorp-tion is seen at velocities pertaining to EIG features infront of the GC along the line of sight

G358616-00076

The H II region has an RRL association with the TiltedDisk or Looping Ridge The H I absorption spectrumconfirms absorption at velocities corresponding to theNear 3kpc Arm only further supporting a location inthe EIG Absorption is also seen at velocities either sideof the expected velocity range of the Tilted Disk

G358623-00066

Like G358616-00076 (above) G358623-00066demonstrates significant absorption associated with theNear 3kpc Arm and Tilted Disk The RRL associationwith the Looping RidgeTilted Disk suggests a locationin the EIG Note the bifurcation in the Near 3kpc Armabsorption profile see sect4

G358633+00062

H I absorption is seen at velocities corresponding to theNear 3kpc Arm and the H I Tilted Disk The positiveRRL velocity suggests either a EIG or near Solar circlelocation absorption corresponding to near-side EIG fea-tures discounts the near-kinematic distance and if theH II region was located near the Solar cirlce on the farside there should be evidence of absorption associatedwith the Far 3kpc Arm As a result it is assumed that theH II region is located within the EIG ie RGal lt 3kpcDlos gt 85kpc Note the bifurcation in the Near 3kpcArm absorption profile (see G358623-00066 above)

G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038

The H I absorption profiles of these H II regions are allsimilar And all have highly non-circular RRL velocities

18

which correspond to the Tilted Disk - G359159-00038has two known RRL velocities (-1825 and -2156 kmsminus1) The H I absorption spectra suffer from emissionfluctuations and are generally of poor quality

G359277-00264

G359277-00264 demonstrates no absorption at veloc-ities corresponding to EIG features a near side KDARis given

G359432-00086

G359432-00086 has a known RRL velocity associatedwith the Near 3kpc Arm The H I absorption spectrumtowards the region demonstrates absorption associatedwith the Near 3kpc Arm (and also at sim minus120km sminus1)

G359467-00172

At this longitude the expected velocity ranges of theNear 3kpc Arm and Tilted Disk overlap The H I ab-sorption spectrum demonstrates absorption at velocitiescorresponding to the Near 3kpc Arm but suffers fromemission fluctuations at the overlap The H II region hasan RRL velocity consistent with either the Tilted Diskor Near 3kpc Arm

G000284-00478

Absorption is present at velocities corresponding to theNear 3kpc Arm but not at the expected velocities ofother EIG features It is assumed that the H II region islocated in the EIG beyond the Near 3kpc Arm RGal lt3kpc Dlos gt 85kpc

G000361-00780

G000361-00780 demonstrates H I absorption at veloc-ities associated with the Near 3kpc Arm but no absorp-tion at other EIG lv features It is therefore assumedas with G000284-00478 above that the H II region is lo-cated within RGal lt 3kpc Dlos gt 85kpc

G000382+00107

With two RRL velocities (257 and 414 km sminus1GBTHRDS) the absorption spectrum is likely to havecontributions from at least emission two sources alongthe line of sight Absorption at the Near 3kpc Arm and+135km sminus1 Expanding Arm velocities suggests that atleast one of the emission sources is located on the far sideof the GC No KDAR is given Note also that at this lon-gitude the expected velocity ranges of the H I Tilted Diskand Far 3kpc Arm are nearly indistinguishable

000510-00051

H I absorption is present at velocities corresponding tothe Near 3kpc Arm but not at the velocities of other EIGfeatures The RRL velocity (45km sminus1 Downes et al(1980)) suggests an association with the Far 3kpc Arm

G000572-00628


G000640+00623

A far-side KDAR is assumed for G000640+00623 dueto absorption at velocities corresponding to both 3kpcArms (and the Tilted Disk)

G000729-00103

G000729-00123 has two recorded RRL velocities(1053 and 832 km sminus1 GBTHRDS) both forbiddenby circular Galactic rotation The region was studiedby Downes et al (1980) who found an RRL velocity of102 km sminus1 Caswell amp Haynes (1987) discussed the H II

region as being clearly located near the EIG but not de-lineating the outer boundary of the Galactic bar TheGBTHRDS find that of their nine H II regions associated(in lv space) with the Nuclear Disk G000729-0103 isthe only source that could be located on the red-shiftedside The H I spectrum demonstrates statistically signifi-cant absorption at velocities corresponding to both 3kpcArms but not for the Nuclear Disk nor +135km sminus1 Ex-panding Arm No H I absorption is present at either ofthe RRL velocities No KDAR is given

G000838+00189

The H I absorption spectrum which is of poor qual-ity due to emission fluctuations demonstrates absorptionconsistent with the velocities expected of each of the EIGfeatures (Near 3kpc Arm H I Tilted Disk +135km sminus1

Expanding Arm and Far 3kpc Arm) A far-side KDARis therefore awarded to the H II region

G001125-00105

Wink et al (1982) remarked that the non-circularRRL velocity (-197 km sminus1) and H2CO at 84 and 123km sminus1 was typical of a EIG source Quireza et al (2006)also give Dlos = 85kpc THe H II region must be locatedwithin the EIG as absorption at EIG features negatesthe near-side kinematic location and if the H II regionmust have a non-realistic RGal gt 45kpc

G001149-00062

G001149-00062 displays absorption at velocities cor-responding to both the Near and Far 3kpc Arms Assum-ing a distance of at least the Far 3kpc Arm G001149-00062 must lie in the outer Galaxy beyond the SolarCircle (due to the negative systemic velocity) Howeverusing a flat rotation model for the outer Galaxy the cal-culated Dlos is unrealistic (sim 50kpc) Therefore the H II

region must lie in the EIG region but behind the Far3kpc Arm

G001324+00104

No H I absorption is seen at velocities correspondingto EIG features suggesting a near KDAR However thenegative RRL velocity (-127 km sminus1 GBTHRDS) sug-gests a location in either the EIG or in the outer Galaxy- locations that each would imply absorption by the Near3kpc Arm which is not seen No KDAR is given

G001330+00088

G001330+00088 has a similar H I absorption profileas G001324+00104 A EIG location is assumed

19

G001488-0199

Caswell et al (2010) assigns a 67 GHz methanol maserat the same velocity to Rgal lt 3 kpc due to the negativesystemic velocity Absorption at velocities correspond-ing to the Near 3kpc Arm supports the Rgal lt 3 kpcplacement

G002009-0680

Dlos gt 5 kpc is assumed due to absorption at Near3kpc Arm velocities

G002404+0068


G002418-0611


G002510-00028

Dlos gt 5kpc is assumed due to absorption at velocitiescorresponding to the Near 3kpc Arm

G002611+00135

For a 67 GHz methanol maser at the same coordi-nates Caswell et al (2010) discuss that the large pos-itive systemic velocity is most readily attributed to alocation within the Galactic bar Absorption is seen atNear 3kpc Arm velocities and at velocities slightly lowerthan the RRL velocity (1024 km sminus1 Lockman (1989))but not at +135km sminus1 Expanding Arm velocities there-fore Rgal lt 3kpc is assumed See Section 6 for a previousdiscussion of this H II region

G002819-00132


G002901-00006

The negative RRL velocity suggests a EIG or outerGalaxy location Absorption at Near 3kpc Arm veloci-ties infers a Dlos gt 5kpc but a lack of absorption as-sociated with any other EIG feature does not allow theEIGouter Galaxy location degeneracy to be resolvedQuireza et al (2006) give a location in the Outer Galaxy

G002961-0053

The H I absorption spectrum is most likely a confusionof multiple H II regions - there are two RRL velocities(181 and -35 km sminus1 GBTHRDS) No KDAR is given

G003270-00101

Absorption at velocities corresponding to both 3kpcArms suggests a kinematic location in or beyond theFar 3kpc Arm The near zero systemic velocity thensuggests a location near the Solar circle Quireza et al(2006) give a line of sight distance to G003270-00101 of14 kpc

G003342-00079

Significant absorption is seen at both the Near and Far3kpc Arms (and at sim 100km sminus1) Using this absorptionas a distance indicator G003342-00079 is given a farKDAR

G003439-0349

G003439-0349 is assumed to be located in the Near3kpc Arm due to RRL and maser velocities (GBTHRDSCaswell et al (2010)) as well as H I absorption at veloc-ities expected of the Near 3kpc Arm

G003449-0647

With H I absorption at Near 3kpc Arm velocitiesDlos gt 5kpc is assumed As the H II region has a nearzero systemic velocity and no absorption associated withthe Far 3kpc Arm then RGal lt 3kpc should also apply

G003655-00111

Absorption at velocities corresponding to the Near3kpc Arm and a near zero RRL velocity (46 km sminus1Lockman (1989)) suggests Rgal lt 3kpc

G003928-00116

Evidence of absorption is present at velocities corre-sponding to both the Near and Far 3kpc Arms As aresult G003928-00116 is given a far side KDAR

G003949-00100

The H I absorption spectrum is of poor quality typicalof the diffuse regions of the Lockman et al (1996) cata-log No KDAR is given however the small RRL velocity(65km sminus1) suggests a possible EIG location

G004346+00115


G004412+00118

Absorption is present at velocities corresponding to theNear and Far 3kpc Arms This suggests a location ofRgal gt 3kpc on the far side of the GC ie a far sideKDAR

G004527-00136

Absorption at Near 3kpc Arm velocities and evidenceof absorption at Far 3kpc Arm velocities suggests a farKDAR

G004568-00118

Absorption at velocities associated with the Near 3kpcArm suggest Dlos gt 5kpc

G005193-00284

Absorption at Near 3kpc and Connecting Arm veloc-ities suggests Dlos gt 7kpc that is the H II region mustbe located behind the Connecting Arm along the line ofsight

20

G005479-00241

Significant absorption is present at velocities associ-ated with both the Near and Far 3kpc Arms resultingin a far side KDAR

G005524+00033

Absorption is present at velocities associated with theNear and Far 3kpc Arms suggesting a far side KDAR

G005633+00240


G005889-00427

Absorption is not seen towards any EIG features sug-gesting a near side KDAR Downes et al (1980) also pro-vided a near side KDAR however Quireza et al (2006)give a line of sight distance of 145 kpc placing the H II

region on the far side of the GC

G006014-00364

There are two RRL velocities reported for G006014-00364 (142 and -319 km sminus1 GBTHRDS) suggestingthat there are multiple sources along the line of sightNo KDAR is given

G006083-00117

Absorption at the 3σeminusτ level is seen at velocities as-

sociated with the Near and Far 3kpc Arms suggestinga far side KDAR In addition absorption at sim +135 ispresent

G006148-00635

The H I absorption spectrum of G006148-00635 doesnot give conclusive evidence for either a near nor farKDAR However absorption is present at velocities as-sociated with the Near 3kpc Arm suggestive of Dlos gt5kpc

G006160-00608

H I absorption is present at velocities corresponding tothe Connecting Arm but not the Near 3kpc Arm (pos-sibly due to emission fluctuations)

G006225-00569

The H I absorption spectrum of G006225-00569 doesnot give conclusive evidence for either a near nor farKDAR As with G006160-00608 absorption is seen atvelocities corresponding with the Connecting Arm butnot the Near 3kpc Arm (which precedes the ConnectingArm along the line of sight)

G006398-00474

Absorption is present at velocities corresponding to theConnecting Arm but not the Near 3kpc Arm (see above)

G006553-00095

Perhaps the most well behaved absorption spectrum inthis work significant absorption is seen in the Near andFar 3kpc Arms as well as the Connecting Arm stronglyindicative of a far side KDAR

G006565-00297

Again there is no absorption seen at velocities cor-responding to the Near 3kpc Arm (see G006160-0060G006225-00569 and G006398-00474 above) but in thiscase the lack of absorption is probably due to emissionfluctuations Absorption at velocities corresponding tothe Connecting and Far 3kpc Arms suggests a far sideKDAR

G006616-00545


G007041+00176

Significant absorption is present at velocities corre-sponding to the Near and Far 3kpc Arms a far sideKDAR is given

G007176+00086


G007254-00073

G007254-00073 has two known RRL velocities (47and 175 km sminus1 GBTHRDS) suggesting multiplesources along the line of sight

G007266+00186

The H I absorption spectrum of G007266+00186demonstrates absorption at velocities associated with theNear 3kpc and Connecting Arms which suggests a loca-tion Dlos gt 7kpc In addition a near zero RRL velocity(-44 km sminus1 GBTHRDS) and a lack of absorption atFar 3kpc Arm velocities suggests Rgal lt 3kpc

G007299-00116


G007420+00366

The H I absorption spectrum of G007420+00366shows absorption at velocities associated with the Nearand Far 3kpc Armsas a result the H II region is given afar side KDAR

G007466-00279

Absorption is present at velocities associated with theNear 3kpc Arm but no further evidence for a KDAR isforthcoming from the H I absorption spectrum

G007472+00060

Significant absorption at velocities corresponding toboth the Near and Far 3kpc Arms strongly suggests afar side KDAR however the RRL velocity (-178km sminus1Lockman (1989)) is indicative of a location in the Near3kpc Arm The H II region also presents significant ab-sorption at sim +135km sminus1 (see G006083-00117 above)

21

G007700-00079

The H II region has two observed RRL velocities oneof which is associated with the velocity expected of theConnecting Arm No KDAR is given

G007768+00014


G007806-00621

Evidence of absorption at velocities corresponding tothe Near 3kpc Arm Connecting Arm implies a distancealong the line of sight as least as far as the ConnectingArm

G008005-00484

Absorption is present at velocities consistent with theNear 3kpc and Connecting Arms but with no other EIGfeatures The lower line of sight distance limit is thereforeDlos gt 7kpc

G008006-00156

Evidence of absorption at velocities corresponding tothe Near 3kpc Arm Connecting Arm and Far 3kpc Armstrongly implies a far side KDAR

G008094+00085


G008103+00340

The H I absorption spectrum of G008103+00340 doesnot give conclusive evidence for either a near nor farKDAR However absorption is present at velocities cor-responding to the Near 3kpc Arm

G008137+00228

Absorption is not seen towards any EIG features sug-gesting a near side KDAR in agreement with Wink et al(1982) and Quireza et al (2006)

G008362-00303

The H I absorption spectrum of G008362-00303 doesnot give conclusive evidence for either a near nor farKDAR However absorption is present at velocities cor-responding to the Near 3kpc Arm

G008373-00352

Absorption is present at velocities consistent with theNear 3kpc and Connecting Arms but with no other EIGfeatures

G008432-00276

Evidence of absorption due to both the Near and Far3kpc Arms suggests a far side KDAR

G008666-00351

Green amp McClure-Griffiths (2011) and Downes et al(1980) both give a near side KDAR for the H II regionA near side KDAR is also given by this work - note thatat this longitude the expected velocity range of the Near3kpc Arm overlaps the expected velocities of general cir-cular rotation

G008830-00715

Absorption is not seen towards any EIG features sug-gesting a near side KDAR

G008865-00323


G009178+00043

There H I absorption spectrum suffers from emissionfluctuations the H II region must be located at least asfar as the Near 3kpc Arm along the line of sight

G009615+00198

Kinematic distance analyses can be greatly affected byvelocity crowding and a decrease of cold dense H I in theEIG For example Sanna et al (2009) thoroughly inves-tigated the high mass star formation region G962+020 -comprised of several H II regions - and find from trigono-metric parallax that it has a distance of 52 plusmn 06 kpcplacing it in the 3 kpc Arm This distance is at oddswith the kinematically determined distances for the re-gion (036 and 164 kpc based on the systemic velocityof the region 41 km sminus1) Inspection of the H I ab-sorption spectrum of G009615+00198 rules out the farkinematic distance as there is no significant absorptionat the velocities of far side EIG features (ie the Far3kpc Arm)

G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752

At this longitude the velocities associated with theNear 3kpc Arm and normal circular rotation overlap NoKDARs are given

REFERENCES

Anderson L D Bania T M Balser D S amp Rood R T2012 ApJ 754 62

Anderson L D Bania T M Balser D S amp Rood R T2011 ApJS 194 32

Anderson L D amp Bania T M 2009 ApJ 690 706Baba J Saitoh T R amp Wada K 2010 PASJ 62 1413Bania T M 1980 ApJ 242 95

Bania T M amp Lockman F J 1984 ApJS 54 513Bania T M Stark A A amp Heiligman G M 1986 ApJ 307

350Bania T M Anderson L D Balser D S amp Rood R T

2010 ApJ 718 L106Bania T M Anderson L D amp Balser D S 2012 ApJ 759 96

22

Blitz L Binney J Lo K Y Bally J amp Ho P T P 1993Nature 361 417

Brand J amp Blitz L 1993 AampA 275 67Burton W B Liszt H S 1983 AampAS 52 63Caswell J L amp Haynes R F 1982 ApJ 254 L31Caswell J L amp Haynes R F 1987 AampA 171 261Caswell J L Fuller G A Green J A et al 2010 MNRAS

404 1029Churchwell E Babler B L Meade M R et al 2009 PASP

121 213Clemens D P 1985 ApJ 295 422Condon J J Cotton W D Greisen E W et al 1998 AJ

115 1693Dame T M Hartmann D amp Thaddeus P 2001 ApJ 547 792Dame T M amp Thaddeus P 2008 ApJ 683 L143Dame T M amp Thaddeus P 2011 ApJ 734 L24Dickey J M McClure-Griffiths N M Gaensler B M amp

Green A J 2003 ApJ 585 801Dickey J M amp Lockman F J 1990 ARAampA 28 215Downes D Wilson T L Bieging J amp Wink J 1980 AampAS

40 379Fux R 1999 AampA 345 787Green J A McClure-Griffiths N M Caswell J L et al 2009

ApJ 696 L156Green J A amp McClure-Griffiths N M 2011 MNRAS 417

2500Green J A Caswell J L McClure-Griffiths N M et al 2011

ApJ 733 27Gooch R 1996 Astronomical Data Analysis Software and

Systems V 101 80Hachisuka K Brunthaler A Menten K M et al 2009 ApJ

696 1981Honma M Bushimata T Choi Y K et al 2007 PASJ 59

889JonesC amp Dickey J 2012 ApJ 753 62Kolpak M A Jackson J M Bania T M Clemens D P amp

Dickey J M 2003 ApJ 582 756Lang C C Goss W M Cyganowski C amp Clubb K I 2010

ApJS 191 275Liszt H S 2008 AampA 486 467

Liszt H S Burton W B 1980 ApJ 236 779Lockman F J 1989 ApJS 71 469Lockman F J Pisano D J amp Howard G J 1996 ApJ 472

173Marshall D J Fux R Robin A C amp Reyle C 2008 AampA

477 L21McClure-Griffiths N M Dickey J M Gaensler B M et al

2005 ApJS 158 178McClure-Griffiths N M amp Dickey J M 2007 ApJ 671 427McClure-Griffiths N M Dickey J M Gaensler B M et al

2012 ApJS 199 12Moises A P Damineli A Figueredo E et al 2011 MNRAS

411 705Morris M amp Serabyn E 1996 ARAampA 34 645Oort J H 1977 ARAampA 15 295Paladini R Burigana C Davies R D et al 2003 AampA 397

213Quireza C Rood R T Bania T M Balser D S amp Maciel

W J 2006 ApJ 653 1226Reid M J Menten K M Zheng X W et al 2009 ApJ 700

137Rodrıguez-Fernandez N J 2006 Journal of Physics Conference

Series 54 35Rodriguez-Fernandez N J Combes F Martin-Pintado J

Wilson T L amp Apponi A 2006 AampA 455 963Rodrıguez-Fernandez N J 2011 Memorie della Societa

Astronomica ItalianaSupplementi 18 195Roy S 2003 AampA 403 917Sanna A Reid M J Moscadelli L et al 2009 ApJ 706 464Sewilo M Watson C Araya E et al 2004 ApJS 154 553Simonson S C amp Madder G L 1973 AampA 27 337Uchida K Morris M amp Yusef-Zadeh F 1992 AJ 104 1533Urquhart J S Hoare M G Lumsden S L et al 2012

MNRAS 420 1656van Woerden H Rougoor G W amp Oort J H 1957 Academie

des Sciences Paris Comptes Rendus 244 1691Wink J E Altenhoff W J amp Mezger P G 1982 AampA 108

227

2

have been made towards several bright or otherwise in-teresting EIG continuum sources (Uchida et al 1992Roy 2003 Lang et al 2010 and references therein) acomplete H I absorption study of the EIG region hasnot been attempted This present H I absorption sur-vey constitutes the most complete study of H I absorptionagainst the continuum emission from the entire sample ofH II regions known with |l| lt 10o This study is only pos-sible due to recent H II region discovery surveys (whichprovide a list of target continuum regions with which tomeasure absorption against) and improved resolution inH I surveys that include the GC regionIn addition to providing a sample of bright continuum

sources against which to measure H I absorption H II

regions also provide an important secondary tracer ofGalactic structure the H II regions themselves Galac-tic H II regions are the formation sites of massive OBstars which have a main sequence lifetime of simtens ofmillions of years As a result Galactic H II regions revealthe locations of current massive star formation indicatethe present state of the ISM provide a unique probeof Galactic chemical evolution and are the archetypi-cal tracers of Galactic spiral structure (Anderson et al2011)In this work we measure HI absorption against only

those HII regions with known radio recombination line(RRL) velocities This sub-sample is discussed in Sec-tion 2 and the method of HI absorption is described inSection 3We then summarise the known EIG structures (Section

41) and their locations in Longitude-Velocity (lv) spaceWe plot these structures on an lsquolv crayon diagramrsquo anduse the diagram to consider the EIG lv distribution ofH I absorption in Section 5 and later for H II regions(Section 6)We combine the results from Sections 5 and 6 to ex-

plore the Galactic distribution of H II regions (Section 7)- through determining the lower limit of the line of sightdistance to each H II region based on its H I absorptionprofile and systemic velocityFinally a discussion of individual sources appears as

Appendix A

2 DATA amp SOURCE SELECTION

Large scale high resolution astronomical surveys arenow publicly available in many wavelength regimes Thiswork uses large-scale H I data and radio continuum maps

21 Radio Continuum

Radio continuum maps were sourced from theNRAO VLA Sky Survey (Condon et al 1998NVSS) and the Southern Galactic Plane Survey(McClure-Griffiths et al 2005 SGPS)The NVSS covers 82 of the sky (north of δ = minus40o)

at 14GHz resulting in 2326 4x4 degree continuum cubesof Stokes parameters and a catalog of continuum emis-sion sources Only the Stokes I maps were used for thiswork It should be noted that the NVSS maps do not in-clude zero spacing (uv) information and therefore manylarger diffuse emission regions particularly those in theLockman et al (1996) catalog are not detected

22 Neutral Hydrogen H I

For this work H I absorption spectra were extractedfrom the two SGPS datasets (5o lt |l| lt 10o) and theATCA H I Galactic Center Survey (5o lt |l| HIGCSMcClure-Griffiths et al 2012) Observations for theSGPS (I amp II) and ATCA HIGCS were performed withthe Australia Telescope Compact Array (ATCA) andsupplemented with data from the Parkes Radio Tele-scope The three surveys provide continuous coverageof the inner Galactic plane (253o lt l lt 20o) at sim2rsquo res-olution

23 Radio Recombination Lines

Catalogues of RRLs provide systemic velocities for H II

regions Large-scale surveys of RRLs from H II regionswere performed during the 1960rsquos to 1980rsquos More re-cently the Green Bank Telescope H II Region Discov-ery Survey (Anderson et al 2011 GBTHRDS) covered343o lt l lt 67o and detected RRLs from 448 new H II

regions effectively doubling the number known in thatlongitude range The GBTHRDS is complete to 180 mJyat 9 GHz and is able to detect all H II regions ionised bya single O-star to a distance of 12 kpcIn addition the GBTHRDS also includes a catalog of

known H II regions as of 2010 For the |l| lt 10o regionthis includes the combined works of Downes et al(1980) Wink et al (1982) Caswell amp Haynes (1987)Lockman (1989) Lockman et al (1996) and Sewilo et al(2004) The GBTHRDS team carefully compiled thisldquoknownrdquo catalog removing duplicate sources throughradio continuum and mid-infrared inspection Howeverthey note that it is ldquolikely to contain some residual con-tamination and duplicate entriesrdquo The combination ofthis ldquoknownrdquo catalog of H II regions and the GBTHRDSsource list within |l| lt 10o provided the sample list ofregions for this work Both the GBTHRDS catalog andthe compilation of previous catalogs can be found at[httpwwwcvnraoeduhrds]httpwwwcvnraoeduhrds

231 H II Regions Selected

There are nearly 200 known H II regions in the range|l| lt 10o |b| lt 15o with observed RRL velocities H I

absorption spectra were extracted towards a total of 151of these H II regions (see Figure Set 1) The remainingH II regions were either not visible in the NVSS contin-uum maps (also used by the GBTHRDS) usually diffuseH II regions from the Lockman et al (1996) catalog orH II regions with coordinates that could refer to severalcontinuum sources - see Table 1 Therefore this study ob-tains H I absorption spectra towards over 80 of knownH II regions with |l| lt 10o The lsquonamersquo for each H II re-gion is taken from the RRL catalog from which it wassourced

3 EXTRACTION OF THE H I ABSORPTIONSPECTRA

The hyperfine transition that creates the 21-cm H I lineis often seen in both emission and absorption from thesame region - indeed for most continuum sources a mix-ture of emission and absorption is observed Therefore amethod is required to separate the two

31 EmissionAbsorption Method

3





(in both catalogs)





Tcont

(2)



eminusτ)














4


















5








as the purple curve








Figure 2


curve














6















































































1 F3= Far 3kpc Arm

7








VF3kpc = +577+402lplusmn 1561 (4)




GALAXY



8



















9





A





















10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

3





(in both catalogs)





Tcont

(2)



eminusτ)














4


















5








as the purple curve








Figure 2


curve














6















































































1 F3= Far 3kpc Arm

7








VF3kpc = +577+402lplusmn 1561 (4)




GALAXY



8



















9





A





















10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

4


















5








as the purple curve








Figure 2


curve














6















































































1 F3= Far 3kpc Arm

7








VF3kpc = +577+402lplusmn 1561 (4)




GALAXY



8



















9





A





















10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

5








as the purple curve








Figure 2


curve














6















































































1 F3= Far 3kpc Arm

7








VF3kpc = +577+402lplusmn 1561 (4)




GALAXY



8



















9





A





















10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

6















































































1 F3= Far 3kpc Arm

7








VF3kpc = +577+402lplusmn 1561 (4)




GALAXY



8



















9





A





















10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

7








VF3kpc = +577+402lplusmn 1561 (4)




GALAXY



8



















9





A





















10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

8



















9





A





















10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

9





A





















10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

10











= Θ0















11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

11















8 SUMMARY


12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

12


13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

13











14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

14

APPENDIX


G350004+00438


G350129+00088


G350177+00017


G350330+00157


G350335+00107


G350524+00960


G350769-00075


G350813-00019


G350996-00557


G351028+00155


G351047-00322


G351192+00708


G351201+00483


G351358+00666


G351359+01014


G351467-00462


G351601-00348


G351662+00518


15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

15

G351691+00669


G352233-00151


G352313-00440


G352398-00057


G352521-00144


G352610+00177


G352611-00172


G352866-00199


G353186+00887


G353218-00249


G353381-00114


G353398-00391


G353557-00014


G354200-00050


G354418+0036


G354486+00085


G354588+00007


16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

16

G354610+00484



G354664+00470


G354665+00247



G354717+00293



G354934+00327


G354979-00528


G355242+00096


G355344+00145




G355532-00100


G355581+00288


G355611+00382


G355696+0350


G355700-00100


G355734+0138


17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

17

G355801-00253


G356230+00066


G356235+00642


G356307-00210


G356470-0001


G356560-00086


G356650+00129


G357484-00036


G357970-00169


G357998-00159



G358319-00414


G358379-00840


G358530+00056


G358552-00025


G358616-00076


G358623-00066


G358633+00062


G358652-00078 G358680-00087 G358694-00075G358720+00011 G358797+00058

G358827+00085 AND G359159-00038


18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

18


G359277-00264


G359432-00086


G359467-00172


G000284-00478


G000361-00780


G000382+00107


000510-00051


G000572-00628


G000640+00623


G000729-00103



G000838+00189



G001125-00105


G001149-00062



G001324+00104


G001330+00088


19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

19

G001488-0199


G002009-0680


G002404+0068


G002418-0611


G002510-00028


G002611+00135


G002819-00132


G002901-00006


G002961-0053


G003270-00101


G003342-00079


G003439-0349


G003449-0647


G003655-00111


G003928-00116


G003949-00100


G004346+00115


G004412+00118


G004527-00136


G004568-00118


G005193-00284


20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

20

G005479-00241


G005524+00033


G005633+00240


G005889-00427



G006014-00364


G006083-00117



G006148-00635


G006160-00608


G006225-00569


G006398-00474


G006553-00095


G006565-00297


G006616-00545


G007041+00176


G007176+00086


G007254-00073


G007266+00186


G007299-00116


G007420+00366


G007466-00279


G007472+00060


21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

21

G007700-00079


G007768+00014


G007806-00621


G008005-00484


G008006-00156


G008094+00085


G008103+00340


G008137+00228


G008362-00303


G008373-00352


G008432-00276


G008666-00351


G008830-00715


G008865-00323


G009178+00043


G009615+00198


G009925-00745 G009682+00206 G009717-00832G009741+00842 G009875-00749 AND

G009982-00752


REFERENCES







22






























227

22






























227

arxiv:1308.2769v1 [astro-ph.ga] 13 aug 2013 · throughout this paper, we refer to the area inside...

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