sub-mm surveys & galaxy formation shades scuba2 jim dunlop university of edinburgh
TRANSCRIPT
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