Extragalactic surveys with CCAT: distant galaxies and nearby templates Contribution from Blain et al.

2 Summary of CCAT’s galaxy science Telescope design optimized for fast wide-field imaging at an excellent site, CCAT can: Find huge numbers of distant galaxies (z~1-5) at rate >10 3 hr -1 Find huge numbers of distant galaxies (z~1-5) at rate >10 3 hr -1 Use colors to sift the sample to find examples with extreme redshifts/luminosities to better understand the way the bulk of galaxy luminosity evolves and confront galaxy formation models Use colors to sift the sample to find examples with extreme redshifts/luminosities to better understand the way the bulk of galaxy luminosity evolves and confront galaxy formation models Resolve the emission from a large sample of low-redshift galaxies to reveal the final, authoritative bolometric galaxy luminosity function to z~0.2, based on SDSS redshifts Resolve the emission from a large sample of low-redshift galaxies to reveal the final, authoritative bolometric galaxy luminosity function to z~0.2, based on SDSS redshifts Covering the whole submm/mm band, it will provide the best possible photo redshifts, based on redshifted far-IR SED peaks CCAT will enhance capability of new facilities Leverage small-field, ultradeep, high-resolution imaging with ALMA by feeding targets to the big interferometer Leverage small-field, ultradeep, high-resolution imaging with ALMA by feeding targets to the big interferometer Easily match the survey area coverage of Herschel Space Observatory to better locate and understand the targets Easily match the survey area coverage of Herschel Space Observatory to better locate and understand the targets Systematically identify all point sources from the Planck all-sky survey Systematically identify all point sources from the Planck all-sky survey Remove point-source confusion from existing/future CMB maps Remove point-source confusion from existing/future CMB maps

3 Dust-enshrouded Universe Orion through telephoto lens (~2 degree field) Resolved in detail only in Milky Way ~50% of all energy absorbed by dust ~50% of all energy absorbed by dust More in molecular star-forming regions Dust cooling is crucial for star formation Most ISM metals in dust Dust is vital ISM component Dust present at z>6 Physics and chemistry of dust still complex and unfinished Molecular gas provides diagnostic information about the most intense regions of star formation ALMA will map it in great detail, but CCAT can provide maps of total power from nearby galaxies

4 Resolved `example’: the Antennae Excellent example of distinct opt/UV and IR luminosity BUT modest luminosity BUT modest luminosity Interaction long known, but great luminosity unexpected ~90% energy escapes at far-IR wavelengths ~90% energy escapes at far-IR wavelengths Resolved images important here to reveal dust location Different structure in hot and cool dust Different structure in hot and cool dust Relevant scales ~1” at high redshift Relevant scales ~1” at high redshift This is a task for ALMA This is a task for ALMA Low redshift examples and identification of high-redshift examples from CCAT Low redshift examples and identification of high-redshift examples from CCAT HST WFPC2 ISOCAM CSO/SHARC-2 Dowell et al.

5 Mm/submm gives direct view out to highest redshifts The mm/submm waveband in the continuum allows direct access to high redshifts CCAT can reach quickly (in minutes) down to sub-mJy flux densities where typical high- redshift galaxies are found Existing surveys reach ~1mJy at 1.2mm, ~5mJy at 0.85mm Existing surveys reach ~1mJy at 1.2mm, ~5mJy at 0.85mm These see only the most luminous galaxies These see only the most luminous galaxies Multi-band imaging with CCAT, expanded further with optical, radio and Spitzer/Herschel observations should identify most distant/interesting by color

6 Obscured galaxies: background Many sources of data Total far-IR and optical background intensity comparable Simple statement of importance of obscured emission Simple statement of importance of obscured emission Most of the submm (0.8mm) background already detected by SCUBA Order of magnitude deeper is enough to catch most of far-IR luminosity Order of magnitude deeper is enough to catch most of far-IR luminosity ISO and more precise, but similar Spitzer limits detect ~20-30% in mid-IR Note: backgrounds yield weaker constraints on evolution than N(S) counts to see next SCUBA ISO Models: BJSLKI 99 SCUBA

7 Populations of galaxies to find Current generations of surveys have identified ~500 high-redshift galaxies at wavelengths of 1.2/1.1/0.85mm ~500 high-redshift galaxies at wavelengths of 1.2/1.1/0.85mm Handful at 0.35/0.45mm Handful at 0.35/0.45mm Redshifts are typically 2-3 Likely to be a relatively rare high- redshift tail Likely to be a relatively rare high- redshift tail Low-redshift galaxies can also be detected Low-redshift galaxies can also be detected Signs of galaxies being clustered more strongly than average galaxies Signs of galaxies being clustered more strongly than average galaxies Current samples too small to define accurate luminosity function Galaxies too luminous to tie them clearly to larger samples at optical wavelengths Galaxies too luminous to tie them clearly to larger samples at optical wavelengths Confusion noise and mapping speed both a problem

8 Global luminosity evolution Points: optical/IR/UV data Blue: optical / UV Blue: optical / UV Red: IR and dust corrected Red: IR and dust corrected Black: SDSS fossil record Black: SDSS fossil record Lines: results from combined submm/far-IR counts & background Note high-z decline certainly real Note high-z decline certainly real Decline less rapid than for QSOs? Decline less rapid than for QSOs?Caveats AGN power (Alexander et al. & Chandra implies low?) AGN power (Alexander et al. & Chandra implies low?) High-z / high-L IMF change High-z / high-L IMF change Submm-selected sample probes most intense epoch of galaxy evolution directly Neo-WMAP cosmology

9 Redshift distribution N(z) for radio-pinpointed SMGs Red histogram: Chapman et al Lines: expected submm & radio N(z)’s from Chapman’s model Consistent with early submm- derived Madau plots but result is now MUCH more robust Consistent with early submm- derived Madau plots but result is now MUCH more robust Magenta shade at z~1.5 is ‘spectroscopic desert’: rest-UV & rest-optical lines both hard to observe Magenta shade at z~1.5 is ‘spectroscopic desert’: rest-UV & rest-optical lines both hard to observe Blue shading at highest z is incompleteness due to radio non-detection. Likely modest, but uncertain Blue shading at highest z is incompleteness due to radio non-detection. Likely modest, but uncertain Now 73 redshifts (ApJ 2005) Median z=2.4 and spread in redshift z~0.65 is good description Median z=2.4 and spread in redshift z~0.65 is good description Chapman et al. (2003; 2005)

10 Luminosity function Based on known redshifts and fraction of population with redshifts (~50%) can see dramatic evolution from z=0 to 1 to 2.5 Plausible connection to the luminosity function of optically-selected high-z galaxies Lower limits from stacked high-z galaxies as only a fraction of far-IR luminous objects are detected in UV surveys Lower limits from stacked high-z galaxies as only a fraction of far-IR luminous objects are detected in UV surveys Interesting to see Spitzer LF results at z~1 for comparison Spectroscopy not trivial at z~1 Spectroscopy not trivial at z~1 Most of luminosity from far-IR luminous galaxies emitted at ~10 12 L o CCAT can reveal this CCAT can reveal this Too faint for existing telescopes Too faint for existing telescopes Chapman et al. (2005); astro-ph/

11 Future tools LMT*-shown SOFIA*/BLAST CARMA AT25 SCUBA-II Herschel*/Planck* ALMA* (and APEX) SPICA SAFIR (JWST-based?)* SPECS/SPIRIT

12 CCAT confusion limits Current missions in black Spitzer is + SOFIA/Herschel are  and  ALMA bar is a 500-m baseline CCAT bar is ground-based 25-m SAFIR is space-borne 10-m Confusion from galaxies not met for many minutes Confusion from galaxies not met for many minutes At shortest wavelengths very deep observations are possible At shortest wavelengths very deep observations are possible Factor of a few increase in resolution over existing facilities is very powerful Reaching sub-mJy fluxes at >500GHz allows connection between optical and existing far-IR galaxies Reaching sub-mJy fluxes at >500GHz allows connection between optical and existing far-IR galaxies Confusion falls away quickly on scales of 5 arcsec and GHz Confusion falls away quickly on scales of 5 arcsec and GHz ▬ ▬ ▬

13 CCAT: Confusion noise Model based on galaxies in SCUBA/ISO populations Also consistent with Spitzer results Also consistent with Spitzer results Galactic cirrus modest here Galactic cirrus modest here Flux for 1 source per beam ~ RMS noise Extragalactic sources dominate for small apertures When < 500µm ~25-m aperture or bigger is very important When < 500µm ~25-m aperture or bigger is very important At fluxes <0.1mJy sure to find submm counterparts to high-z optical galaxies At fluxes <0.1mJy sure to find submm counterparts to high-z optical galaxies

14 Survey speed / time Large format cameras essential to rapid mapping Gain from ALMA is approximately product of bandwidth and pixel number Gain from ALMA is approximately product of bandwidth and pixel number This can be a huge number This can be a huge number Also huge compared with existing facilities Also huge compared with existing facilities And essential part of CCAT program is developing these instruments Sky is large enough for a 25-year program Submm spectroscopy will always be of a subset of the detections Natural role for ALMA Natural role for ALMA Wide-field optical design will enable future development of multi-object spectroscopy Wide-field optical design will enable future development of multi-object spectroscopy Imaging is prime goal. ALMA can provide resolved imaging and spectroscopy of the detections CCAT provides enough color information to help to sift targets for ALMA CCAT provides enough color information to help to sift targets for ALMA

15 Mapping speed comparing other facilities CCAT is an ultrafast mapper Assumptions pixel detector, Nyquist sampled at all bands 0.2, 0.35, 0.45, 0.67, 0.85,1.1mm (in order from violet-red) pixel detector, Nyquist sampled at all bands 0.2, 0.35, 0.45, 0.67, 0.85,1.1mm (in order from violet-red) Observationally verified counts (good to factor 2) Observationally verified counts (good to factor 2) Confusion and all sky limits Confusion and all sky limits 1.2/0.85/0.35mm imaging speeds are compatible To reach confusion at 0.35mm go several times deeper at 0.85mm To reach confusion at 0.35mm go several times deeper at 0.85mm Detection rates are  150  SCUBA-2;  300  ALMA  150  SCUBA-2;  300  ALMA About per hour About per hour Lifetime detection of order galaxies: ~1% of ALL galaxies! Lifetime detection of order galaxies: ~1% of ALL galaxies! `1/3 sky survey’: ~1000 deg -2 for 3 deg 2 hr -1 gives 5000 hr `1/3 sky survey’: ~1000 deg -2 for 3 deg 2 hr -1 gives 5000 hr

16 Detection rate in surveys Note the comparable detection rate in different atmospheric windows Multi-band detection rate can be quantified, but most are detected in more than one band Knowledge about SED comes from two bands in submm, not a great deal gained by getting more. Not true in optical or mid-IR Knowledge about SED comes from two bands in submm, not a great deal gained by getting more. Not true in optical or mid-IR There is a limit to a deep survey, imposed by confusion ALMA will go deeper ALMA will go deeper Limit is about local L* Limit is about local L* Wide survey limited just by the elevation/latitude Number of ‘extreme’ and lensed objects for detailed and easy ALMA study will come from here Number of ‘extreme’ and lensed objects for detailed and easy ALMA study will come from here Spitzer will reveal luminosity function in enough detail to plan the intermediate depth survey cones Design limits from aperture and field of view respectively These are being driven to best possible These are being driven to best possible

17 SEDs: full & zoom of IRAC-24 region SED peak wave-length ranges over factor 3 No nice stellar SED peak in IRAC, no neat spectral breaks/features... All SMG far-IR photometric redshifts will need care Other information from optical/near-IR color will be valuable to obtain better constraints. CCAT should be considered in context. Normalised to 60 & 100 quantity from the far-IR:radio relation IRAC & MIPS-24 zoomed plot Radio-far-IR relation seems to hold OK

18 ‘Photometric redshifts’ from dust SEDs Can combine different bands to estimate T & z together No strong far-IR spectral breaks or features No strong far-IR spectral breaks or features 24mm band can see redshifted PAH emission lines and Si absorption features from dust grains 24mm band can see redshifted PAH emission lines and Si absorption features from dust grains Plot shows flux ratio against Spitzer MIPS 70mm Strongest lever from µm Strongest lever from µm Based on better knowledge of galay properties from Spitzer and weather at CCAT site, can probably design optimal band shapes to do photo-z’s Once z known, get accurate luminosity ALMA can do this too (a few galaxies at a time), combined with real redshift information from submm spectral lines Color cf 70  m from Spitzer

19 Galaxies at lower redshifts Can resolve images of ~4000 galaxies larger than 30 arcsec across in a single CCAT pointing 10kpc is >30 arcsec at distances 30 arcsec at distances < 60Mpc, which encloses ~4000 galaxies, and is most of the way to the Coma cluster Resolve GMCs on 2-10 arcsec scales for ALMA single pointing followup of most enshrouded/active regions Resolve GMCs on 2-10 arcsec scales for ALMA single pointing followup of most enshrouded/active regions Interacting galaxies on 30kpc scales can have extent of 0.35mm emission measured to >1Gpc / z~0.25 True local luminosity function, including cold dust not easy to select using IRAS images Interesting synergy with ASTRO-F/IRIS all-sky survey, which is available in years? Interesting synergy with ASTRO-F/IRIS all-sky survey, which is available in years? Also WISE allsky 12 & 24  m survey in 2009/2010 Also WISE allsky 12 & 24  m survey in 2009/2010