Large-scale structure in wide-Large-scale structure in wide-field far-IR surveysfield far-IR surveys

Andrew Blain Andrew Blain

CaltechCaltech

1818thth March 2008 March 2008

Moriond Cosmology

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ContentsContentsAccurate measurements of large-scale structure provides constraints on wide range of Accurate measurements of large-scale structure provides constraints on wide range of cosmology questions. Want to see growth from z>7 to 0cosmology questions. Want to see growth from z>7 to 0

– Multiwavelength approach: radio/mm SZ; near-IR/optical starlight; X-ray gasMultiwavelength approach: radio/mm SZ; near-IR/optical starlight; X-ray gas– Traced out by luminous matter: HI & X-ray gas, stars, dust…Traced out by luminous matter: HI & X-ray gas, stars, dust…– Weak lensing offers pure mass-based selection now, in future mass measurements.Weak lensing offers pure mass-based selection now, in future mass measurements.

But, even if cosmology is known, we will still don’t understand the details of galaxy assembly, But, even if cosmology is known, we will still don’t understand the details of galaxy assembly, and the effects of environmentand the effects of environment

Likely most important in regular bound clusters: established in the biased high-z regions where Likely most important in regular bound clusters: established in the biased high-z regions where clusters will eventually formclusters will eventually form

Dust reprocesses about 50% of the energy released over the Universe’s historyDust reprocesses about 50% of the energy released over the Universe’s history– Less now than at z~2Less now than at z~2– Both star formation and AGN activity are responsibleBoth star formation and AGN activity are responsible– Accompanied by molecular (and fine-structure atomic) gas emissionAccompanied by molecular (and fine-structure atomic) gas emission– More important at greater luminosities, especially >10More important at greater luminosities, especially >101313 L Loo

Identifying structure from the presence of the most luminous galaxies (SMGs)Identifying structure from the presence of the most luminous galaxies (SMGs)

Identifying distant LSSIdentifying distant LSS

SZ can work, X-ray is toughSZ can work, X-ray is toughMost luminous dusty galaxies at high-z (SMGs) seem to be Most luminous dusty galaxies at high-z (SMGs) seem to be clustered strong clustering, likely to indicate their location in clustered strong clustering, likely to indicate their location in the densest regions the densest regions – Mechanism for triggering extreme luminosity?Mechanism for triggering extreme luminosity?

Identify very luminous galaxies:Identify very luminous galaxies:– To study their astrophysics To study their astrophysics – To signpost the densest regionsTo signpost the densest regions– To understand foreground map for CMB experimentsTo understand foreground map for CMB experiments

Discover from Spitzer, ground-based submmDiscover from Spitzer, ground-based submm– Locate using radio image (ultimately ALMA)Locate using radio image (ultimately ALMA)– Find redshift in optical (ultimately ALMA)Find redshift in optical (ultimately ALMA)

Integrated extragalactic backgroundIntegrated extragalactic background

Many sources of dataMany sources of dataTotal far-IR and optical Total far-IR and optical background intensity are background intensity are comparablecomparableMost of the submm Most of the submm (0.8mm) background is (0.8mm) background is detected from luminous detected from luminous galaxies at z~2-3galaxies at z~2-3Everywhere background Everywhere background known to about a factor of known to about a factor of 22

SCUB

A

Model: BJSLKI ‘ Models: BJSLKI 99

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

Red histogram: Chapman et al’s Keck Red histogram: Chapman et al’s Keck redshiftsredshiftsLines: expected submm & radio N(z)’s Lines: expected submm & radio N(z)’s from Chapman’s modelfrom Chapman’s model– 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

73 redshifts73 redshifts– 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. (2005 ApJ 622 772)

Clustering: expectations & modelsClustering: expectations & modelsN-body simulations track N-body simulations track mass well (greyscale)mass well (greyscale)Red labelled galaxies Red labelled galaxies (ellipticals) form earlier, (ellipticals) form earlier, and are most clusteredand are most clusteredRelating submm galaxies Relating submm galaxies is more difficult, and not is more difficult, and not so far done convincinglyso far done convincingly

z=2Prediction difficulties:

Strong feedback

Rare well-studied examples

Uncertain astrophysics 1 Mpc ~ 100 arcsec at high z

SMGs trace 3D large-scale structure (LSS) peaks?SMGs trace 3D large-scale structure (LSS) peaks?

Largest number of SMGs are in and Largest number of SMGs are in and around the HDF-Naround the HDF-N– HDF & GOODS frames show HDF & GOODS frames show

where morphology information where morphology information is available is available

Circles: all known radio-submm Circles: all known radio-submm galaxiesgalaxies– Small empty: no z attemptSmall empty: no z attempt– Large empty: no z found Large empty: no z found – Black filled: z foundBlack filled: z found– Colored filled: ‘associations’ - Colored filled: ‘associations’ -

all z’s within 1200 km/sall z’s within 1200 km/sGreen points (z=1.99) match optical Green points (z=1.99) match optical galaxy z spike (Steidel et al)galaxy z spike (Steidel et al)Only the spectroscopic redshifts Only the spectroscopic redshifts from Keck’s LRIS reveal structurefrom Keck’s LRIS reveal structureMany more ‘clusters’ or Many more ‘clusters’ or associations than expected from our associations than expected from our knowledge of SMG N(z)knowledge of SMG N(z)

Comparison with other populationsComparison with other populations

Other more numerous high-z populations are Other more numerous high-z populations are less clusteredless clusteredAre SMG redshift associations linked to Are SMG redshift associations linked to overdensities of other more numerous galaxy overdensities of other more numerous galaxy classes at the same redshift? classes at the same redshift? – Links with optically selected galaxies at z~2 in Links with optically selected galaxies at z~2 in

HDFHDF– Narrow-band imaging with Keck-LRIS has Narrow-band imaging with Keck-LRIS has

found associated line-emitting optical galaxies found associated line-emitting 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

– Keck-OSIRIS resolved spectra will be excitingKeck-OSIRIS resolved spectra will be exciting

After Overzier et al. (2003)

Highlighting overdense regionsHighlighting overdense regions

Correlation length suggests very massive halosCorrelation length suggests very massive halos– Although small number of fields / areaAlthough small number of fields / area

But, abundance of massive halos is too great in these narrow But, abundance of massive halos is too great in these narrow (10’) pencil beams by factor of ~10-100(10’) pencil beams by factor of ~10-100Reason for bias could tell us about triggering the most Reason for bias could tell us about triggering the most luminous galaxiesluminous galaxiesFollow-up imaging identifies distribution of less-luminous Follow-up imaging identifies distribution of less-luminous companions companions Follow-up spectroscopy identifies velocity dispersion, Follow-up spectroscopy identifies velocity dispersion, astrophysicsastrophysicsWider-field surveys - SCUBA-2, HerschelWider-field surveys - SCUBA-2, HerschelDeeper surveys - CCAT, ALMADeeper surveys - CCAT, ALMAShorter wavelengths (stars & hot dust) - Spitzer, WISEShorter wavelengths (stars & hot dust) - Spitzer, WISE

WISE (PI Ned Wright)WISE (PI Ned Wright)

Launch May 2009Launch May 2009– Final Delta II/III flightFinal Delta II/III flight

All-sky survey from All-sky survey from outward-looking low earth outward-looking low earth orbitorbit– 47 arcmin swath47 arcmin swath– Hope for 2.5 6-month all-sky Hope for 2.5 6-month all-sky

mapsmaps

3.5, 4.9, 12, 24 3.5, 4.9, 12, 24 mmDepth similar to SWIREDepth similar to SWIREFinder for JWSTFinder for JWSTLSS via 3.5/4.9 colors and LSS via 3.5/4.9 colors and 24 24 m catalogm catalog

~0.4m aperture1k2 detectors

wise.ssl.berkeley.edu

CCAT: future submm telescopeCCAT: future submm telescope

Existing submm facilities are limited to Existing submm facilities are limited to ~2mJy sensitivities by confusion noise~2mJy sensitivities by confusion noise– CSO JCMT APEXCSO JCMT APEX

Note ALMA has great sensitivity, but small Note ALMA has great sensitivity, but small field of view field of view Large format detectors are possible Large format detectors are possible – SCUBA-2 soon to be deployed with SCUBA-2 soon to be deployed with

4x64x40 bolometers4x64x40 bolometers– Zmuidzinas et al’s ‘kinetic inductance Zmuidzinas et al’s ‘kinetic inductance

devices’ - microwave addressed detectors devices’ - microwave addressed detectors using mobile phone switch technology - could be >>1000using mobile phone switch technology - could be >>10002 2 pixelspixels

– Detectors for a larger single-aperture ground-based telescope, and Detectors for a larger single-aperture ground-based telescope, and moving towards a large space-based cold aperture telescopemoving towards a large space-based cold aperture telescope

Caltech-Cornell Atacama Telescope (CCAT) study (submm.org)Caltech-Cornell Atacama Telescope (CCAT) study (submm.org)– Best possible site, and atmospheric transmission to 200 micronsBest possible site, and atmospheric transmission to 200 microns– Wide field of view (~30 arcmin) to accommodate new detector Wide field of view (~30 arcmin) to accommodate new detector

technologytechnology

SummarySummaryMost luminous galaxies seem to be found in densest regionsMost luminous galaxies seem to be found in densest regions

Highlighting these regions should allow many clusters to be Highlighting these regions should allow many clusters to be foundfound

Understanding astrophysics of galaxy formation requires this Understanding astrophysics of galaxy formation requires this work, independent of whether LSS is revealedwork, independent of whether LSS is revealed

Area surveyed will soon grow Area surveyed will soon grow – 2008 SCUBA-2 survey plans (but follow-up painful)2008 SCUBA-2 survey plans (but follow-up painful)– 2009 Herschel ~600 square degrees (OT key project Eales)2009 Herschel ~600 square degrees (OT key project Eales)– 2009 Planck - all sky, bright point high-z sources 2009 Planck - all sky, bright point high-z sources

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

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CO examplesCO examples

K band image (8” square), with IRAM CO contours of an ultraluminous galaxy at z=3.35

Genzel et al. (2004)

SAFIR field SAFIR field exceeds extent of exceeds extent of the ISO image, the ISO image, yet has spatial yet has spatial resolution as good resolution as good as the as the inteferometer, inteferometer, plus spectral plus spectral information information

Upper: submm continuum; lower optical HSTAbell 851

Tacconi et al (2006), Neri et al. (2003), Greve et al. (2005)

25x25”

30x30” 10x10”

SEDs: full & zoom of IRAC-24 regionSEDs: full & zoom of IRAC-24 region

SED peak wave-length ranges SED peak wave-length ranges over factor 3over factor 3No nice stellar SED peak in No nice stellar SED peak in IRAC, no neat spectral IRAC, no neat spectral breaks/features...breaks/features...All SMG photometric redshifts All SMG photometric redshifts need careneed care

Normalised to 60 & 100 quantity from the far-IR:radio relation

IRAC & MIPS-24 zoomed plotRadio-far-IR relation seems OK

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

Example IDed submm galaxyExample IDed submm galaxy

Relatively bright in optical, complexRelatively bright in optical, complexMay not see most important region in the optical - May not see most important region in the optical - Spitzer IRAC can also highlight interesting locationsSpitzer IRAC can also highlight interesting locationsBoth J1n & J2 are at z = 2.55 – radio and mm appear to Both J1n & J2 are at z = 2.55 – radio and mm appear to be from J1nbe from J1n

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

Narrow band

20”x20” 6”x6”

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

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

Morphologies for examples of SMGsMorphologies for examples of SMGs

GOODS images of SMGs with GOODS images of SMGs with redshifts 3.4-1.9redshifts 3.4-1.9– Only radio detected Only radio detected

examples included, so examples included, so positions accuratepositions accurate

Wide range of sizes, but Wide range of sizes, but ttypically larger than ypically larger than optically-selected galaxies optically-selected galaxies at same redshiftat same redshiftRange of colors, typically Range of colors, typically interacting and complexinteracting and complexAll detected by Spitzer-IRACAll detected by Spitzer-IRAC– Often as double sourcesOften as double sources

Smail et al. (2004) ApJ, 616, 71Borys et al (in prep)

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”

▬▬▬

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 galaxy SED of galaxy SED propertiespropertiesNon-thermal radioNon-thermal radio– Radio-far-IR linkRadio-far-IR link

Thermal dust Thermal dust dominates dominates luminosity luminosity Molecular & fine Molecular & fine structure lines carry structure lines carry redshift, dynamical, redshift, dynamical, and physical and physical informationinformation

Normalized where sizeable sample of `submm galaxies’ are selected. Redshifts z~2-3 from Chapman et al.

Luminosity functionLuminosity function

Based on known redshifts and Based on known redshifts and fraction of population with fraction of population with redshifts (~50%) can see redshifts (~50%) can see dramatic evolution from z=0 to dramatic evolution from z=0 to 1 to 2.51 to 2.5Plausible connection to the Plausible connection to the luminosity function of optically-luminosity function of optically-selected high-z galaxiesselected high-z galaxies– Lower limits as only a Lower limits as only a

fraction of far-IR luminous fraction of far-IR luminous objects are detected in UV objects are detected in UV surveyssurveys

Key goal to better understand Key goal to better understand astrophysics of galaxy astrophysics of galaxy formation is overall high-z LFformation is overall high-z LF

Chapman et al. (2005 ApJ 622 772)