Sub-mm surveys & galaxy formationSub-mm surveys & galaxy formationSHADES SCUBA2SHADES SCUBA2

Jim DunlopUniversity of Edinburgh

Outline

1.Overview of current survey situation

2.Some science – final results from SHADES

3.SCUBA2 Cosmology Legacy Survey

Mauna Kea Observatory, HawaiiMauna Kea Observatory, HawaiiThe James Clerk Maxwell sub-mm telescopeThe 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 microns50 square arcmin simulation based on BLAST counts courtesy of Ed Chapin

Problem is that sub-mm telescopes have been getting much more sensitivebut 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 sourcesDunlop et al. (2009) arXiv:0910.3642

Truth is, SCUBA2 & Herschel complement each other perfectly

Herschel needed for bolometric luminosities.

SCUBA2 needed to fully exploit Herschel maps (especiallyat 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 ingalaxy 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 www.roe.ac.uk/ifa/shades

Dunlop 2005, astro-ph/0501419

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 maps2 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. 2006

Estimated background of sources >2mJy is ~9700 mJy/deg2

>20-30% of FIRB resolved

Theory/model challenge 1Theory/model challenge 1Make enough sub-mm galaxiesMake 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 redshiftsIdentifications and redshifts

Radio and mid-infraredRadio 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)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

RedshiftsRedshifts

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 850.5 – Wang et al. 2008

COSMOS AzTEC 1 – Younger et al. 2007

GN20 – Iono et al. 2006Younger et al. 2008Daddi et al. 2009

SFR > 1000 Msun yr -1

SFR > 2000 Msun 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 2Theory/model challenge 2Make brightest sub-mm galaxies at high zMake brightest sub-mm galaxies at high z

then stop it….

The nature of sub-mm galaxiesThe nature of sub-mm galaxies

Stellar masses – Schael et al. 2009; Dunlop et al. 2009

Sub-mm sources are already massive: > 1011 solar masses

CO dynamical masses suggest

~1011 Msun within r ~ 2 kpc (Tacconi et al. 2006)

We find typical stellar masses

~ 3 x 1011 Msun and typical r0.5 = 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

Mstar >1011 Msun : 1 x 10-4 Mpc-3

SFR > 500 Msun yr -1 : 2 x 10-5 Mpc-3

SFR > 1000 Msun yr -1 : 3 x 10-6 Mpc-3

SFR > 2000 Msun yr -1 : 1 x 10-6 Mpc-3

1-3 x 10-5 Mpc-3 is number density of 2-3 L* ellipticals today

Stellar masses from 2-comp fittingStellar masses from 2-comp fitting

Observed starburst only adding ~10% of mass

Predicted redshift distribution of earlier starburstsPredicted redshift distribution of earlier starbursts

OK, but if really starbursts – 100 mJy SCUBA sources!

Theory/model challenge 3 Theory/model challenge 3 Make large galaxy stellar mass before Make large galaxy stellar mass before

observed starburstobserved starburst

and hide it…

Are 2-component models stupid?Are 2-component models stupid?

All that the current photometric data justifies

Higher time-resolution predictionsHigher time-resolution predictions

Detailed star-formation historiesDetailed star-formation histories

Morphologies – Targett et al. 2009

Sub-mm galaxies are mainly discs

Radio galaxies are r1/4 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 likeellipticals/bulges than present-day star-forming discs

Theory/model challenge 4 Theory/model challenge 4 Evolve massive dense disc galaxies into Evolve massive dense disc galaxies into

today’s giant ellipticalstoday’s giant ellipticals

Future prospectsFuture 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 Strategy2-year plan: fields dictated by multi-freq follow-up and accessibility

20 sq degree 850 micron survey to rms = 0.7 mJyXMM-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)

0.6-0.9 sq degree 450 micron survey to rms = 0.5 mJyGOODS-N (0.05 sq deg), GOODS-S (0.05-0.25 sq deg), UDS (0.25 sq deg), COSMOS (0.25 sq deg), SA22 (0.02 sq deg), AKARI NEP (0.02 sq deg)

0.6-0.9 sq degree 850 micron survey to rms = 0.15 mJyGOODS-N (0.05 sq deg), GOODS-S (0.05-0.25 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

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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