Sub-mm surveys & galaxy formation SHADES SCUBA2 Jim Dunlop University of Edinburgh

Outline 1.Overview of current survey situation 2.Some science – final results from SHADES 3.SCUBA2 Cosmology Legacy Survey

Mauna Kea Observatory, Hawaii The James Clerk Maxwell sub-mm telescope

2009 – no new data from the JCMT….. but a BIG year for mm-far-infrared extragalactic astronomy BLAST surveys at 250,350,500 microns (Devlin et al. 2009) Halpern, Chapin, Viero talks Laboca surveys at 870 microns (Weiss et al. 2009a) Chapin talk AzTEC surveys at 1.1mm (e.g. Austermann et al. 2009) Aretxaga and Wilson talks First CO redshifts (Daddi et al. 2009, Weiss et al. 2009b) Walter talk More detailed high-resolution results from SMA and IRAM PdB (e.g. Younger et al. 2009, Bothwell et al. 2009) Tacconi talk Herschel commencing HERMES and ATLAS surveys Oliver & Clements talks First ALMA antennas on site Rawlings talk LMT dish finally taking shape Hughes talk SCUBA2 commissioning on JCMT, and first call for proposals

Why do we still care about the JCMT? Resolution comparison of BLAST, Herschel and JCMT at 500/450 microns 50 square arcmin simulation based on BLAST counts courtesy of Ed Chapin Problem is that sub-mm telescopes have been getting much more sensitive but also smaller We didn’t feel this pain with HST, because ground-based optical telescopes weren’t diffraction limited, nor with Spitzer because ground-based high-z mid- infrared astronomy didn’t really exist

Galaxy spectrum at progressively higher redshifts Also, longer wavelengths offer a clear view from z = 1 to z = 8 (reionization?)

Redshift distribution of faint 250-micron BLAST sources Dunlop et al. (2009) arXiv:

Truth is, SCUBA2 & Herschel complement each other perfectly Herschel needed for bolometric luminosities. SCUBA2 needed to fully exploit Herschel maps (especially at high-redshift) and to establish secure galaxy counterparts So, we need both to explore the cosmic history of dust- enshrouded star-formation and the role of this activity in galaxy formation.

Finishing off SHADES The nature of sub-mm galaxies in the multi-wavelength context Key challenges to theory, which larger surveys will refine

SHADES An attempt to put extragalactic sub-mm astronomy on a solid footing. The first complete, unbiased, large area, sub-mm survey Aim to determine number counts, redshift distribution, clustering, and other basic properties of the bright (~8 mJy) sub-mm population RATIONALE Available dynamic range with JCMT is limited So stay bright – 8 mJy unconfused maximum chance of effective follow-up massive starbursts = big challenge to theory

SHADES Dunlop 2005, astro-ph/ van Kampen et al. 2005, MNRAS, 359, 469 Mortier et al. 2005, MNRAS, 363, 563 Coppin et al. 2006, MNRAS, 372, 1621 Aretxaga et al. 2007, MNRAS, 379, 1571 Ivison et al. 2007, MNRAS, 380, 199 Takagi et al. 2007, MNRAS, 381, 1154 Coppin et al. 2007, MNRAS, 384, 1597 Dye et al. 2008, MNRAS, 386, 1107 Serjeant et al. 2008, MNRAS, 386, 1907 Clements et al. 2008, MNRAS, 387, 247 Younger et al. 2008, MNRAS, 387, 707 Van Kampen et al. 2009, in prep Schael et al. 2009, in prep Dunlop et al. 2009, in prep + AzTEC papers to follow...

SHADES SCUBA 850-micron maps 2 fields – Lockman Hole & SXDF/UDS 4 independent reductions combined to produce one SHADES catalogue 120 sources with unbiased (deboosted) flux densities

Number counts Coppin et al Estimated background of sources >2mJy is ~9700 mJy/deg 2 >20-30% of FIRB resolved

Theory/model challenge 1 Make enough sub-mm galaxies

New SHADES AzTEC 1.1mm maps (Austerman et al. 2009)

850-micron contours on 1.1mm greyscale Joint SCUBA+AzTEC source extraction now being explored (Negrello et al. 2010)

Identifications and redshifts

Radio and mid-infrared Radio and mid-infrared Ivison et al. (2007) 25 x 25 arcsec stamps VLA radio contours on R-band Subaru image, and Spitzer 24-micron image 85-90% of the 120 sources identified via VLA and/or Spitzer

The Smithsonian Sub-millimeter Array (SMA)

Importance of SMA if no unambiguous radio ID e.g. SXDF850.6 (Hatsukade et al. 2009) SMA on optical SMA on K-band Demonstrates 1.power of sub-mm interferometry (Younger et al. 2007,2008) 2.importance of near-IR data identification & study of host galaxy

Redshifts

Redshifts 4 different forms of redshift information: Spectroscopic – Chapman et al., Stevens et al. Far-infrared to radio – Carilli & Yun, Aretxaga et al. Optical – near-infrared – Dye et al., Clements et al. Spitzer – Pope et al. In SHADES only ~20% of sources currently have an unambiguous spectroscopic z

Deep near-ir data crucial for photometric redshifts

GOODS – Wang et al COSMOS AzTEC 1 – Younger et al GN20 – Iono et al Younger et al Daddi et al SFR > 1000 M sun yr -1 SFR > 2000 M sun yr -1

Evidence of down-sizing: Clear that the comoving number density of > 5 mJy sub-mm sources peaks in redshift range 2 < z < 3 Brightest (>12 mJy) sources lie at 3 < z < 4 < 5mJy sources span much wider z range

SFR versus cosmic time – epoch of massive galaxy formation

Theory/model challenge 2 Make brightest sub-mm galaxies at high z then stop it….

The nature of sub-mm galaxies

Stellar masses – Schael et al. 2009; Dunlop et al S ub-mm sources are already massive: > solar masses

CO dynamical masses suggest ~10 11 M sun within r ~ 2 kpc (Tacconi et al. 2006) We find typical stellar masses ~ 3 x M sun and typical r 0.5 = 2-3 kpc Is this sensible?

You’d expect such a big starburst to be hosted by an already massive galaxy Daddi et al. (2007) SFR v stellar mass relation at z = 2

Number densities at 2 < z < 3 M star >10 11 M sun : 1 x Mpc -3 SFR > 500 M sun yr -1 : 2 x Mpc -3 SFR > 1000 M sun yr -1 : 3 x Mpc -3 SFR > 2000 M sun yr -1 : 1 x Mpc x Mpc -3 is number density of 2-3 L* ellipticals today

Stellar masses from 2-comp fitting Observed starburst only adding ~10% of mass

Predicted redshift distribution of earlier starbursts OK, but if really starbursts – 100 mJy SCUBA sources!

Theory/model challenge 3 Make large galaxy stellar mass before observed starburst and hide it…

Are 2-component models stupid? All that the current photometric data justifies

Higher time-resolution predictions

Detailed star-formation histories

Morphologies – Targett et al Sub-mm galaxies are mainly discs Radio galaxies are r 1/4 spheroids

Image Stack ~50 hr UKIRT image of z = 2 radio galaxy ~20 hr Gemini image of z = 2 submm galaxy

Sub-mm and radio galaxies in the mass-density : mass plane - following Zirm et al. (2006) Sub-mm galaxies Radio galaxies

Sub-mm galaxies appear to be massive gas rich discs completing the formation of their cores. They seem destined to evolve into the massive ellipticals, awaiting relaxation and further extended mass growth by a factor ~ 2 (via dryish mergers?). But in terms of density, they are much more like ellipticals/bulges than present-day star-forming discs

Theory/model challenge 4 Evolve massive dense disc galaxies into today’s giant ellipticals

Future prospects Larger, deeper samples with complete SEDs - Herschel, SCUBA2, LMT, CCAT Complete IR identifications, redshifts, masses - UKIDSS, Ultra-VISTA, Spitzer, FMOS, KMOS Detailed high-resolution spectroscopy - ALMA, JWST

Cosmology Legacy Survey Jim Dunlop (Edinburgh), Mark Halpern (UBC), Ian Smail (Durham), Paul van der Werf (Leiden)

SCUBA2 Survey Strategy 2-year plan: fields dictated by multi-freq follow-up and accessibility 20 sq degree 850 micron survey to rms = 0.7 mJy XMM-LSS (5 sq deg), Lockman Hole (4 sq deg), CDFS (3 sq deg), ELAIS N1 (2 sq deg), COSMOS (2 sq deg), BOOTES (2 sq. deg), EGS (1 sq deg), AKARI NEP (1 sq deg) sq degree 450 micron survey to rms = 0.5 mJy GOODS-N (0.05 sq deg), GOODS-S ( sq deg), UDS (0.25 sq deg), COSMOS (0.25 sq deg), SA22 (0.02 sq deg), AKARI NEP (0.02 sq deg) sq degree 850 micron survey to rms = 0.15 mJy GOODS-N (0.05 sq deg), GOODS-S ( sq deg), UDS (0.25 sq deg) COSMOS (0.25 sq deg), SA22 (0.02 sq deg), AKARI NEP (0.02 sq deg) Cosmology Legacy Survey

50 Survey Status Cosmology Legacy Survey Tri-national consortium of ~100 astronomers 490 hrs of band-1 time awarded to the 450 micron survey in semesters 10A,10B,11A, 11B (=90% of all band-1 time) 630 hrs of band-2/3 time awarded to the 850 micron survey in semesters 10A,10B,11A, 11B (Current JCMT agreement expires in 2012!) Consortium agreement in place with Herschel HERMES SCUBA2 – one of 4 arrays in place and working Shared risk proposals now in the queue ready to go Fingers firmly crossed – all arrays expected by the spring