bielby & shanks 2007 mnras submitted

Bielby & Shanks 2007 MNRAS submitted

ROSAT sample of 30 low z clusters Chanda sample of 38 z=0.3 clusters

Interstellar Neutral Hydrogen Emission Structure and Radio

Frequency Continuum Radiation (WMAP) Signals

• Gerrit L. VerschuurPhysics DepartmentUniversity of Memphis

Hydrogen line (HI) data side-lobe corrected

• H-line is a spectral signature at 1,420 MHz or 21-cm wavelength of hydrogen gas between the stars

• Used the Leiden-Dwingeloo All Sky Survey• Hartmann & Burton (1997)• Sidelobe corrected• Plus some from LAB Survey - Kalberla et al. (2005)

• All data will be displayed in galactic coordinates - longitude (l) & latitude (b)

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Galactic longitude (°)

Galactic latitude (°)

20 40 60 80Whole_area__20_to__10_rs

Target Area -20 to -10 km/s

Low velocity

I used 25 HI maps like this to explore the relationship betweenHI and WMAP structure in this area of sky

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0.02.55.07.510.012.515.017.520.022.525.027.5Whole_area__130to_1290_rs

Whole area -130 to -120 km/s 1:28 @ 2

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WMAP pruned, raw data .08 : 0.22 @ 0.03

WMAP +ve contours 0.08 : 0.22 @ 0.02 mK

Overlay WMAP +ve contours on HI inverted gray-scale map

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0.02.55.07.510.012.515.017.520.022.525.027.5Whole_area__130to_1290_rs

Whole area -130 to -120 km/s 1:28 @ 2

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WMAP pruned, raw data .08 : 0.22 @ 0.03HI -130 to -120 km/s

In general, anomalous vel. HI are in the proximity of WMAP peaks.

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0 10 20K.km/s

HI -130 to -120 km/s

Inverted grayscale - HI Contours WMAP peaks

Peak at -126 km/s

Peak at -116 km/s

A possible model -1

Depending on how the line-of-sight intersects the colliding HI features, we may expect to observe alignment of WMAP peaks and HI peaks, or offset peaks

Intercloud plasma

(a) (b)

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V= - 118 km/s v= - 87 km/s

Calculate expected number of associations

• Probability that a given WMAP peak will lie within a distance r of an HI peak located in an area A is:

• r2 A-1

• But we have many WMAP peaks and very many HI peaks at different velocities

Calculate expected number of associations

• Nwpeaks = 33 consider the 33 brightest• Nhpeaks ~ 550/3 ~ 183 visible over 3 maps on

average• N= number of cases where direct

association is expected in this area, A (=4,800 square degrees)

• N = r2 A-1 NWpeaks NHpeaks.

Not chance coincidenceTable

Number of Associations between HI and ILC Peaks: Prediction versus Observation

Target Area Comparison Area Predicted Observed Predicted Observed Direct Association 0.2 10 0.1 0 (within 0.°2) Close offsets 5.1 11 5.9 4 (within ~ 1 deg) (within ~ 1.5 deg) ______________________________________________________________

What did this show?

• For the 1st time, high velocity and intermediate velocity HI structures have been found to be directly associated

• They both appear to be associated with a lack of low-velocity HI

• All three are associated with enhanced continuum emission

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0 2 4 6l145_b60_area__93to_91_kms_rs

l=145, b=60 area -93 to -91 km/s

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HVC MI neutral hydrogen data

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5

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HVC MI -140 to -100 km/s 5 : 100 @ 10

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HI v = -140 to -100 km/s

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v = -140 to -100 km/s

H

HI - inverted gray-scale

WMAP +ve contours

A possible model -1

Depending on how the line-of-sight intersects the colliding HI features, we may expect to observe alignment of WMAP peaks and HI peaks, or offset peaks

Intercloud plasma

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This lead to a prediction in November, 2006 HVC MII will be associated with continuum emission

HVC MI

Excess softX-ray emissionHerbstmeier et al.

HI contours

Testing a prediction HVC MII would show something similar to HVC MI

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HVC MII -70 to -60 km/s 2 : 30 @ 2

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HVC MII v = -70 to -60 km/s

Using WMAP ILC data obtained in December, 2006:

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HVC MII v = -70 to -60 km/s

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194 192 190 188 186 184 182 180

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MII zoom -70 to -60 km/s 2 : 30 @ 2

Soft X-ray excesses

H excess

At the location of the WMAP peaks, the HI profiles are double peaked

Overlay WMAP +ve contours on HI inverted gray-scale map

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0.02.55.07.510.012.515.017.520.022.525.027.5Whole_area__130to_1290_rs

Whole area -130 to -120 km/s 1:28 @ 2

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WMAP pruned, raw data .08 : 0.22 @ 0.03HI -130 to -120 km/s

In general, anomalous vel. HI are in the proximity of WMAP peaks.

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Readily Identified Associations between HI & WMAP Peaks (~0.03mK to 0.06 mK)

HI maps made at 4 km/s intervals, each map covered a 2 km/s widthWMAP contours were plotted from 0.02 mK at 0.02 mK intervals

Galactic Coordinates of Area mapped

(°)

Area in Square degrees

Velocity rnage of HI maps

(km/s)

Number of weak WMAP

peaks in Area

Number with clearly

associated HI peak

Number of those closely aligned

128,-39 450 -94 to +22 14 12 4110, -38 300 -78 to +26 1 1145, -65 500 -82 to +18 2 2100, -55 450 -78 to +22 13 10 1235, -65 300 -74 to +10 1 0157, -52 400

-142 to + 110 4 3 1

40, 60 800 -94 to +14 5 4 150, 40 400 -98 to +38 13 11 250, -45 600 -70 to +22 16 8 3

30, -50 200 -154 to -78

-42 to +2 2 2Totals: 71 53 12

NOTES:1. It became immediately obvious that the weak WMAP peaks are associated with weak HI peaks. 2. All associations are closely spaced, slightly offset, unless otherwise indicated3. Velocity ranges of available maps determined by extent of HI emission inn specific areas.4. Area values not corrected for galactic latitude

5. The Target Area was also examined for this Table but there are too many associations to count, which is why I initially avoided the weak peaks and focussed on the brighter WMAP peaks. They more readily revealed information about interstelllar HI properties.

6. I have to hand several more areas plotted two months ago, to be examined later!

Overview

• Since December I have used WMAP data kindly provided by Gary Hinshaw and Wayne Landsman and compared those data with over 500 HI maps at 2 km/s intervals for small regions of sky.

• The pattern that has emerged is that when the WMAP peak is clearly associated with HI more than one HI feature is involved

• Collisions?

Conclusions: general

• Welcome Back to the Galaxy!

• WMAP small-scale structure may have a significant contribution from foreground features associated with HI structure

• It is possible that all the small-scale WMAP continuum emission structure has a Galactic origin

• By examining HI structure in the direction of WMAP continuum emission peaks at intermediate and high galactic latitudes the study of galactic HI is suddenly made very interesting

Suggestions for the future

• Convert young cosmologists to the study of interstellar structure

• . . . . before they get lost in the cosmos• Extend study to other areas of the sky - a vast

opportunity for new discovery• It is likely that plasma phenomena are key to

understanding interstellar structure • Invite plasma physicists to meet with

astrophysicists studying interstellar structure to create common ground

Reports

• Further Evidence for the Critical Ionization Velocity Signature in Interstellar Neutral Hydrogen Emission Profiles

• IEEE Transaction on Plasma Science - August 2007• This paper offers an explanation for the mechanism for

producing weak continuum emission at the interface between colliding HI features

• High Galactic Latitude Interstellar Neutral Hydrogen Structure and Associated High Frequency Continuum Emission

• Being reviewed for Astrophysical Journal

Acknowledgments

• Dap Hartmann & Butler Burton for providing the LDS All-Sky Survey data last century

• Wayne Landsman of the WMAP group for providing WMAP ILC data for the Target Area in a form I could use (uniform l-b grid)

• Butler Burton for his encouragement and valuable discussions

• Joan Schmelz for her encouragement, valuable discussions, critical readings of my MSs, comments on PPTs, and understanding of the key issues

• Tom Dame for his “holy grail” program using a data cube that allowed

me to make HI maps with ease • Richard Lieu and Jonathan Mittaz for helpful discussions

Hole in local HI at the location of the HI peaks at high and intermediate velocities

This has never before been observed

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10 15 20 25 30K. km/s

v- -8 to +2 km/s

bielby & shanks 2007 mnras submitted

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