ALMA and distant galaxiesALMA and distant galaxies

Andrew Blain Andrew Blain

CaltechCaltech

55thth June 2006 June 2006

AAS Meeting Calgary

ContentsContentsALMA will be a tremendously powerful ALMA will be a tremendously powerful transformationaltransformational tool for all astrophysics tool for all astrophysics

– 50 12-m antenna, with baselines from 15 to 20000m50 12-m antenna, with baselines from 15 to 20000m– Resolution down to of order 10 m-arcsec (10-20x better than current) Resolution down to of order 10 m-arcsec (10-20x better than current) – Sensitivity of order 1mJy in 1s (30x better than existing arrays)Sensitivity of order 1mJy in 1s (30x better than existing arrays)

ALMA makes a day to minute integration time transformationALMA makes a day to minute integration time transformation

– Field of view is antenna primary beam, of order 10-30 arcsec, so ALMA is unique for:Field of view is antenna primary beam, of order 10-30 arcsec, so ALMA is unique for:spectroscopic imaging of individual 1-5 arcsec scale galaxies spectroscopic imaging of individual 1-5 arcsec scale galaxies Ultradeep surveys (possible in parallel with deep pointed observations)Ultradeep surveys (possible in parallel with deep pointed observations)

ALMA has Design Reference Science Plan (DRSP) giving an outline of possibilities (and ALMA has Design Reference Science Plan (DRSP) giving an outline of possibilities (and demands on the program) for 3 yearsdemands on the program) for 3 years

– http://www.strw.leidenuniv.nl/~alma/drsp.htmlhttp://www.strw.leidenuniv.nl/~alma/drsp.html– 40% of DRSP (10,500 hr ~ 14 months) is for extragalactic work40% of DRSP (10,500 hr ~ 14 months) is for extragalactic work

largest suggested programs were cut to meet the 3-year goallargest suggested programs were cut to meet the 3-year goal2000 hr of the extragalactic total is for local group and nearby AGN2000 hr of the extragalactic total is for local group and nearby AGN

– GOODS, COSMOS… provide abundance of targets for 5-10 year ALMA’s programGOODS, COSMOS… provide abundance of targets for 5-10 year ALMA’s program

What is ALMA’s unique role in studying galaxy evolution? What is ALMA’s unique role in studying galaxy evolution? – Resolution matched to HST/JWST; unlimited depthResolution matched to HST/JWST; unlimited depth– Sensitivity to detect normal galaxies at z~3, & extremes prior to reionizationSensitivity to detect normal galaxies at z~3, & extremes prior to reionization– Full spectrum view of galaxy evolutionFull spectrum view of galaxy evolution

ALMA’s UniverseALMA’s Universe

Orion through telephoto lens(~2 degree field)

Detail resolved so far only in Milky Detail resolved so far only in Milky WayWay ~50% of all AGN and starlight ~50% of all AGN and starlight absorbed by dustabsorbed by dust– More in molecular star-forming More in molecular star-forming

regionsregions– Dust cooling is crucial for Pop-I star Dust cooling is crucial for Pop-I star

formationformation– Extremely strong effect on visible Extremely strong effect on visible

morphology: ‘activity-light’ ratiomorphology: ‘activity-light’ ratio

Dust present at z>6Dust present at z>6Combined with molecular gas Combined with molecular gas rotational and atomic fine structure rotational and atomic fine structure emissionemissionPhysics and chemistry of dust is Physics and chemistry of dust is complex and ill constrainedcomplex and ill constrained– But, SED accessible through But, SED accessible through

atmospheric windows is well knownatmospheric windows is well known

Observed far-IR/submm SEDsObserved far-IR/submm SEDsMix of different Mix of different sources traces out sources traces out somesome of the range of the range of SEDs propertiesof SEDs properties– Milky Way & Milky Way &

APM08279 are APM08279 are extremesextremes

Non-thermal radioNon-thermal radio– Radio-far-IR linkRadio-far-IR link

Thermal dust Thermal dust dominates dominates luminosity luminosity CO, HCN, HCO+, C CO, HCN, HCO+, C fine structure lines fine structure lines carry redshift, carry redshift, dynamical, and dynamical, and physical informationphysical informationNormalized where sizeable sample of `submm galaxies’

are selected. Redshifts z~2-3 from Chapman et al.

Resolved ‘example’: the AntennaeResolved ‘example’: the Antennae

Excellent example of distinct opt/UV and Excellent example of distinct opt/UV and IR luminosity; BUT modest luminosityIR luminosity; BUT modest luminosity

Interaction long known, but great IRAS Interaction long known, but great IRAS luminosity unexpected luminosity unexpected

– ~90% energy escapes at far-IR ~90% energy escapes at far-IR wavelengths wavelengths

Resolved images important Resolved images important

– Relevant scales ~1” at high Relevant scales ~1” at high redshift redshift

HST WFPC2Multiband optical

ISOCAM 15m

CSO/SHARC-2Dowell et al. 350m

Spitzer IRAC mid-IR

Distant galaxies at ALMA wavelengthsDistant galaxies at ALMA wavelengthsA significant population of very luminous high-redshift galaxies show powerful far-IR emission - A significant population of very luminous high-redshift galaxies show powerful far-IR emission - submillimeter galaxies (SMGs)submillimeter galaxies (SMGs)– Discovered at submm wavelengths (Smail et al 1997)Discovered at submm wavelengths (Smail et al 1997)– Most located by VLA in the radio, leading to redshifts from Keck optical spectra (Chapman et Most located by VLA in the radio, leading to redshifts from Keck optical spectra (Chapman et

al 2003, 2005) al 2003, 2005) – information fed back for detailed studies of gas using CO/Hinformation fed back for detailed studies of gas using CO/H spectroscopy at spectroscopy at

millimeter/near-IR wavelengths using OVRO MMA, IRAM, Keck, Gemini, GBT… (Tacconi et millimeter/near-IR wavelengths using OVRO MMA, IRAM, Keck, Gemini, GBT… (Tacconi et al. 2006) al. 2006)

While the sample is relatively small (~100), they appear to be strongly clustered, and could be a While the sample is relatively small (~100), they appear to be strongly clustered, and could be a valuable and efficient probe of high-redshift large-scale structure valuable and efficient probe of high-redshift large-scale structure There are signs of massive host galaxiesThere are signs of massive host galaxies– Stellar & dynamical masses from optical/IR images & mm/near-IR spectraStellar & dynamical masses from optical/IR images & mm/near-IR spectra– Aided by information from HST NICMOS & ACS morphologies to reduce uncertainties from Aided by information from HST NICMOS & ACS morphologies to reduce uncertainties from

color gradients / multiple componentscolor gradients / multiple componentsCan they be connected with Spitzer-selected objects?Can they be connected with Spitzer-selected objects?– Yes, but their Spitzer colors have a large scatterYes, but their Spitzer colors have a large scatter

And with optically-selected galaxies? And with optically-selected galaxies? – Yes, but their luminosity functions do not Yes, but their luminosity functions do not yetyet overlap significantly overlap significantly

ALMA will provide a unified picture of the luminosity function of galaxies at high redshift ALMA will provide a unified picture of the luminosity function of galaxies at high redshift

Unique mm/submm access to Unique mm/submm access to highest zhighest z

Redshift the steep submm SEDRedshift the steep submm SEDCounteracts inverse square law Counteracts inverse square law dimmingdimmingDetect high-z galaxies as easily as Detect high-z galaxies as easily as those at z~0.5those at z~0.5– Low-z galaxies do not dominate Low-z galaxies do not dominate

submm imagessubmm images– Unique high-z access in mm and Unique high-z access in mm and

submmsubmm

Ultimate limit at z~10 is set by Ultimate limit at z~10 is set by CMB heatingCMB heating

2mJy at 1mm ~5x102mJy at 1mm ~5x101212 L Loo

– Note matches current depth of Note matches current depth of submillimeter surveyssubmillimeter surveys

– ALMA has no effective limit to ALMA has no effective limit to depthdepth

Example of current single-antenna submm Example of current single-antenna submm imageimage

Abell 1835Abell 1835– Hale 3-color opticalHale 3-color optical– 850-micron SCUBA850-micron SCUBA

Contrast:Contrast:– Image resolutionImage resolution– Visible populationsVisible populations– Orthogonal submm and Orthogonal submm and

optical viewsoptical viewsOne of 7 images from Smail One of 7 images from Smail et al. SCUBA lens survey et al. SCUBA lens survey (97-02)(97-02)– About 25 other SCUBA About 25 other SCUBA

cluster images cluster images – Both bright sources have Both bright sources have

redshifts (2.5 and 2.3; redshifts (2.5 and 2.3; Ivison et al. 2000 & G P Ivison et al. 2000 & G P Smith priv comm)Smith priv comm)Ivison et al. (2000) 2.5’ square

Population of dusty galaxiesPopulation of dusty galaxies

Most data is at 850 Most data is at 850 µµmm– New bright limit from Barnard New bright limit from Barnard

et al (0405156)et al (0405156)– Very few are Galactic Very few are Galactic

contaminating cloudscontaminating clouds

First 2.8mm limit from BIMAFirst 2.8mm limit from BIMABright 95 (&175) Bright 95 (&175) µµm counts m counts from ISO being dramatically from ISO being dramatically improved at 70 & 160 improved at 70 & 160 µµm by m by Spitzer (started August 04 Spitzer (started August 04 ApJS)ApJS)Also recent data at 1.2mm Also recent data at 1.2mm (IRAM’s MAMBO); 1.1mm (IRAM’s MAMBO); 1.1mm (CSO’s BOLOCAM) and (CSO’s BOLOCAM) and 350/450350/450µm (SCUBA & µm (SCUBA & SHARC-2)SHARC-2)

Orange stars – Barnard et al (2004) 850-µm upper limits

***

Obscured galaxies: backgroundObscured galaxies: background

Many sources of dataMany sources of dataTotal far-IR and optical Total far-IR and optical background intensity background intensity comparablecomparableMost of the submm (0.8mm) Most of the submm (0.8mm) background was detected background was detected by SCUBAby SCUBAISO and more precise (but ISO and more precise (but similar) Spitzer limits detect similar) Spitzer limits detect ~20-30% in mid-IR~20-30% in mid-IRNote: backgrounds yield Note: backgrounds yield weaker constraints on weaker constraints on evolution than countsevolution than counts

SCUB

A

ISO

Model: BJSLKI ‘ Models: BJSLKI 99SC

UBA

Spitzer MIPS/IRAC

Redshift distribution N(z) for radio-Redshift distribution N(z) for radio-pinpointed SMGspinpointed SMGs

Red histogram: Chapman et alRed histogram: Chapman et alLines: expected submm & radio N(z)’s Lines: expected submm & radio N(z)’s from Chapman’s modelfrom Chapman’s model– Consistent with early submm-Consistent with early submm-

derived Madau plots but result is derived Madau plots but result is now now MUCHMUCH more robust more robust

– Magenta shade at z~1.5 is Magenta shade at z~1.5 is ‘spectroscopic desert’: rest-UV & ‘spectroscopic desert’: rest-UV & rest-optical lines both hard to rest-optical lines both hard to observe observe

– Blue shading at highest z is Blue shading at highest z is incompleteness due to radio non-incompleteness due to radio non-detection. Likely modest, but detection. Likely modest, but uncertainuncertain

Now 73 redshifts (Now 73 redshifts (ApJ 2005)ApJ 2005)– Median z=2.4 and spread in Median z=2.4 and spread in

redshift redshift zz~0.65 is good description~0.65 is good description

Chapman et al. (2003; 2005)

Global luminosity evolutionGlobal luminosity evolution

PointsPoints– Blue: optical / UV Blue: optical / UV – Red: IR and dust correctedRed: IR and dust corrected– Black: SDSS fossil recordBlack: SDSS fossil record– Uncertainty remainsUncertainty remains

Lines: Lines: – results from combined results from combined

submm/far-IR informationsubmm/far-IR information– Note high-z decline certainNote high-z decline certain– Less rapid than for QSOs?Less rapid than for QSOs?

CaveatsCaveats– AGN power (modest?)AGN power (modest?)– High-z / high-L IMF changeHigh-z / high-L IMF change

Submm-selected sample Submm-selected sample probes most intense epoch of probes most intense epoch of galaxy evolution directlygalaxy evolution directly

WMAP cosmology

Example IDed submm galaxyExample IDed submm galaxy

Relatively bright, complex exampleRelatively bright, complex exampleMay not see most important region in the optical - Spitzer IRAC can highlight May not see most important region in the optical - Spitzer IRAC can highlight interesting locationsinteresting locationsJ2 is a Lyman-break galaxy (Adelberger & Steidel 2000)J2 is a Lyman-break galaxy (Adelberger & Steidel 2000)J1 is a cluster member post-starburst galaxy (Tecza et al. 2004)J1 is a cluster member post-starburst galaxy (Tecza et al. 2004)– HH/continuum ratio imply this does not add significant magnification/continuum ratio imply this does not add significant magnification– J1n is an Extremely Red Object (ERO; Ivison 2001)J1n is an Extremely Red Object (ERO; Ivison 2001)– Remains red in deeper Keck-NIRC dataRemains red in deeper Keck-NIRC data– Powerful HPowerful H emission emission

Both J1n & J2 are at z = 2.55 – radio and mm appear to be from J1nBoth J1n & J2 are at z = 2.55 – radio and mm appear to be from J1n

Ivison et al (2000, 2001); Swinbank et al. (2004)

Narrow band

20”x20” 6”x6”

Best achievable now - distantBest achievable now - distantOnly marginal spatial Only marginal spatial resolution possibleresolution possibleSpectral bandwidth Spectral bandwidth narrownarrowSituation will improve Situation will improve dramatically with ALMA, a dramatically with ALMA, a step in imaging quality step in imaging quality tested at CARMA & IRAMtested at CARMA & IRAM

8’x8’ field PdB HCO+(5-4) Garica-Burillo et al (2006)

Genzel et al PdB

Local example of best resultsLocal example of best resultsIRAM PdB CO in IRAM PdB CO in NGC 6946 NGC 6946 (Schinner et al. (Schinner et al. 2006)2006)Spatial structure & Spatial structure & gas dynamics gas dynamics ALMA can probe ALMA can probe at z~3at z~3– Resolution Resolution – Primary beamPrimary beam

Note synergy with Note synergy with eVLAeVLA– Ultimately SKAUltimately SKA

Red: CO; green: H; blue: continuum

CO(1-0)

CO(2-1)

CO(2-1) contoursHST: Pa & I band

Comparison with other populationsComparison with other populations

Other more numerous high-z populations have Other more numerous high-z populations have less powerful clusteringless powerful clusteringAre SMG redshift associations linked to Are SMG redshift associations linked to overdensities of more numerous galaxy overdensities of more numerous galaxy classes at the same redshift? classes at the same redshift? – At z~2.5 spectroscopy essential to testAt z~2.5 spectroscopy essential to test– Links with ‘BX’ optically selected galaxies at z~2 Links with ‘BX’ optically selected galaxies at z~2

in HDFin HDF– Narrow-band imaging with LRIS in March to Narrow-band imaging with LRIS in March to

search for associated optical galaxies search for associated optical galaxies

Do they reside in such massive halos? Do they reside in such massive halos? – Not every 10’ field can contain such an objectNot every 10’ field can contain such an object– What is the nature of the biasing process?What is the nature of the biasing process?– Near-IR spectra hint at central 4-kpc dynamical Near-IR spectra hint at central 4-kpc dynamical

masses of few 10masses of few 101111MMoo

– Stellar population fitting implies few 10Stellar population fitting implies few 101010MMo,o,but but uncertainties from complex morphologyuncertainties from complex morphology

– OSIRIS resolved spectra will be excitingOSIRIS resolved spectra will be excitingAfter Overzier et al. (2003)

SMGs have a wide range of multiwavelength SMGs have a wide range of multiwavelength propertiesproperties

To better probe their nature, cause and descendents To better probe their nature, cause and descendents need larger samples and more powerful toolsneed larger samples and more powerful tools– Deeper and wider surveys (CCAT)Deeper and wider surveys (CCAT)– Efficient spectrographs at mm/submm/IR wavelengths to Efficient spectrographs at mm/submm/IR wavelengths to

augment optical line work (ALMA) augment optical line work (ALMA)

Goals are to Goals are to – Link optical and submm populations togetherLink optical and submm populations together– Understand environmental factors Understand environmental factors

ALMA cosmolgy: imaging of ALMA cosmolgy: imaging of clustersclusters

A2218 HST & Keck-ESI

Very faint z=5.5 object shows what can be seen along high-magnification critical lines in all clusters

Simulation shows some of the swarm of faint sources expected in the cluster centre if the potential strongly peaked

Einstein radius for z~2

Excellent probes of clusters’ Excellent probes of clusters’ strong lensing when ALMA’s strong lensing when ALMA’s angular resolution is availableangular resolution is available

Red: cluster membersBlue: background galaxiesAlso diffuse SZ effect

Einstein radius for z~2

Other (near-) future toolsOther (near-) future tools

See also Spitzer & Akari

*-shownCARMA*, APEX*, SOFIA*, SCUBA-II, LMT, Herschel*, Planck*, WISE*, ALMA*, CCAT*, SPICA,SAFIR (JWST-based?)*SPECS/SPIRIT

QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.

SummarySummaryALMA will provide spectral and spatial resolution ALMA will provide spectral and spatial resolution to image regions of galaxies where stars are to image regions of galaxies where stars are forming and blackholes are fueling most forming and blackholes are fueling most intensely at z~2-3 intensely at z~2-3 Galaxies can be studied from z=0.1 to beyond Galaxies can be studied from z=0.1 to beyond reionizationreionizationSpectral data will allow unprecedented accuracy Spectral data will allow unprecedented accuracy for derived dynamical massesfor derived dynamical massesDetailed pre-reionization scienceDetailed pre-reionization scienceExploiting gravitational telescopesExploiting gravitational telescopes

Near-IR spectroscopy (NIRSPEC, VLT and Near-IR spectroscopy (NIRSPEC, VLT and narrow-band at IRTF & UKIRT)narrow-band at IRTF & UKIRT)

25 targeted25 targeted– Optical redshifts allow Optical redshifts allow

near-IR spectroscopy in near-IR spectroscopy in favorable sky favorable sky windows windows

HH/[NII] ratios and H/[NII] ratios and H line widths provide hints line widths provide hints at presence of AGNat presence of AGNComposite spectrum of examples with Composite spectrum of examples with narrow (<400km/s) Hnarrow (<400km/s) H show underlying show underlying broad line; narrow component gives broad line; narrow component gives dynamical mass - few 10dynamical mass - few 101111 M Moo

Adding [OII]/[OIII] ratios could bring in Adding [OII]/[OIII] ratios could bring in metallicity, but very time consuming!metallicity, but very time consuming!Aim to target brightest examples with OSIRIS Aim to target brightest examples with OSIRIS to measure detailed dynamicsto measure detailed dynamics

Swinbank et al. 2004

CCAT: Speed vs other instrumentsCCAT: Speed vs other instrumentsALMA, SCUBA-2, 50-m LMT, ALMA, SCUBA-2, 50-m LMT, HerschelHerschelAssume CCAT cameras Assume CCAT cameras – 1100, 870, 740, 620, 450, 350, 1100, 870, 740, 620, 450, 350,

200 microns200 microns– SWCAM 32000 pixelsSWCAM 32000 pixels– LWCAM 16000 pixelsLWCAM 16000 pixels

Fastest depth ~few mJy at Fastest depth ~few mJy at 11001100 microns microns– FOV 25 arcminFOV 25 arcmin22

– 1mJy 51mJy 5σσ in 30s in 30s– 1/2-sky survey in 2.5 yr1/2-sky survey in 2.5 yr– 101088 galaxies galaxies

Confusion limited (350micron)Confusion limited (350micron)– 0.05mJy 10.05mJy 1σσ in 600s in 600s– 2 deg2 deg22 in 40hr in 40hr– 101066 galaxies over few yr galaxies over few yr

Huge galaxy surveysHuge galaxy surveysCMB foreground mapsCMB foreground maps

Overcoming confusionOvercoming confusion

Current missions in blackCurrent missions in black– Spitzer is +Spitzer is +

Green bar is just a 500m Green bar is just a 500m baseline baseline ALMAALMAPurple bar is ground-based 25-Purple bar is ground-based 25-m m CCATCCATRed bar is 10-m Red bar is 10-m SAFIRSAFIR– Confusion from galaxies not Confusion from galaxies not

met for many minutes or hoursmet for many minutes or hours– At shortest wavelengths very At shortest wavelengths very

deep observations are possibledeep observations are possible

Factor 2 increase in resolution Factor 2 increase in resolution over existing facilities is very over existing facilities is very powerfulpowerful– Submm confusion dives at 5”Submm confusion dives at 5”

▬▬▬

X-ray reveals AGN in 2-Ms HDFX-ray reveals AGN in 2-Ms HDF2-Ms exposure reaches 1% of 2-Ms exposure reaches 1% of typical QSO X-ray flux at z~2.5typical QSO X-ray flux at z~2.5

X-ray flux of SMGs implies X-ray flux of SMGs implies significant AGN powersignificant AGN power

19 galaxies in GOODS-N fieldRedshifts allow stacking in soft & hard classes

Excellent fit to X-ray SED models - Fe emission & H absorption

Alex

ande

r et a

l. (2

005a

,b)

SMGs with z’s: FIR-radio assumedSMGs with z’s: FIR-radio assumed

Blain, Barnard & Chapman 2003 & Chapman et al. 2003

Solid circles: newSubmm sources

Radio loud caveat above ~60KSquares: low-z, Dunne et al.

Empty circles: moderate z,mainly Stanford et al.

Crosses: variety of known redshifts(vertical = lensed)

Solid circles: Chapman SMGs

Lines: low-z trends

Scatter in T by at least ~40%