1. Exploring massive galaxy evolution with the UKIDSS Ultra-deep Survey Ross McLure, Michele Cirasuolo, Jim Dunlop (Edinburgh), Omar Almaini, Sebastien Foucaud (Nottingham),

2. Outline Understanding galaxy formation Understanding galaxy formation Why we need deep NIR surveys Why we need deep NIR surveys UKIDSS & the Ultra Deep Survey UKIDSS & the Ultra Deep Survey UDS science results (Edinburgh) UDS science results (Edinburgh) The future: UDSz + spUDS The future: UDSz + spUDS

3. The motivation for UDS: Understanding galaxy formation

4. ΛCDM cosmological model in excellent agreement with wide range of observations: e.g. CMB, galaxy clustering, SN, element abundances, Cepheid distance scale, stellar ages, baryon fraction in clusters, etc… Understanding galaxy formation Cosmology

5. Understanding galaxy formation still don’t understand galaxy formation Cosmology

6. Semi-analytic Galaxy Formation Models + Messy physics (gas cooling, star-formation, AGN, dust, feedback etc…) N-body merger trees = Understanding galaxy formation SAMs have been very successful in some regards traditionally SAMs predicted very few old/red/massive galaxies at high-redshift (i.e. z>1 ) HOWEVER

7. Semi-analytic Galaxy Formation Models + Messy physics (gas cooling, star-formation, AGN, dust, feedback etc…) N-body merger trees = Understanding galaxy formation Over the last 5 years, near-infrared surveys have discovered substantial populations of evolved galaxies at z>1 which are missed by optical surveys, and not accounted for by SAMs (e.g. EROs, DRGs etc)

8. What are they? What are they? n ~50% old, passive systems n ~50% dusty starburst n Strongly clustered n High space density Many old, massive galaxies Many old, massive galaxies already in place at z~1-1.5 already in place at z~1-1.5 e.g. Daddi et al. 2002; Roche, Almaini et al. (2002), Cimatti et a. (2003); Roche, Dunlop & Almaini (2003), Somerville et al. (2003) EROs (Extremely Red Objects)

9. – 6 arcmin 2 – VLT ISAAC imaging (JHK) – K~23.5 (Vega) Find population consistent with very red z>2 galaxies. “Distant Red Galaxies (DRGs)” J - K > 2.3 J - K > 2.3 Labbe et al. 2002, Franx et al. 2003, Rudnick et al. 2003, Van Dokkum et al. 2005, Wuyts et al. 2007 Pushing IR surveys to z>2 FIRES - a glimpse of what UDS will achieve 100 hrs on VLT in 0.5” seeing

10. Understanding galaxy formation Various high-z populations (EROs, DRGs, BzKs etc) all just sub-sets of substantial population of massive galaxies at high-z Better to study evolution of entire galaxy population down to a given K-band limit K<23.5(AB) sample in GOODS-S, Caputi et al. (2006) This study, and others, demonstrated that ~80% of most massive galaxies are in place at z=1, but that only ~10% are in place at z=3 Epoch of massive galaxy formation is 1<z<3 Example: how many >10 11 solar mass galaxies are in place at high redshift? Conclusion:

11. The need for deep infrared surveys Optical surveys sample rest-frame UV at high-z Deep near-IR surveys vital for a complete census at z>1 1. Biased against high-z galaxies obscured by dust 2. Bias against high-z galaxies with old stellar populations 3. Provide poor estimate of stellar mass

12. Outline Understanding galaxy formation Understanding galaxy formation Why we need deep NIR surveys Why we need deep NIR surveys UKIDSS & the Ultra Deep Survey UKIDSS & the Ultra Deep Survey UDS science results (Edinburgh) UDS science results (Edinburgh) The future: UDSz + spUDS The future: UDSz + spUDS

13. UKIDSS : UKIRT Infrared Deep Sky Survey UKIRT (Mauna Kea, Hawaii) Wide-field Camera (WFCAM)

14. UKIDSS design (5 surveys) UKIDSS design (5 surveys) Ultra Deep SurveyUDSJHKK=23.00.77 deg 2 ExGal Deep Extragalactic SurveyDXSJKK=21.035 deg 2 ExGal Galactic Plane SurveyGPSJHKK=19.01800 deg 2 Gal Galactic Clusters SurveyGCSZYJHKK=18.71600 deg 2 Gal Large Area SurveyLASYJHKK=18.44000 deg 2 ExGal UKIRT Infrared Deep Sky Survey

15. WFCAM Focal Plane configuration Four 2048x2048 pixel Rockwell detectors 0.4” pixels give 0.2 square degree in single shot Four exposures give filled 0.8 square degrees 0.88 deg. UDS is one WFCAM tile at RA = 02 18 00, Dec = -05 00 00 (equatorial, 8hrs away from COSMOS field)

16. The UKIDSS Ultra-Deep Survey Depths achieved so far: ) (AB, 5 , 2" apertures) 0.88 deg. EDR: K=22.6, J=22.6 (~12 hours) (~12 hours) Year 1: K=23.5, J=23.6 (~85 hours) (~85 hours) Already deepest IR survey over this area… Already deepest IR survey over this area… Year 3: K=24.2, H=24.0, J=24.3 Year 3: K=24.2, H=24.0, J=24.3 (~250 hours) (~250 hours) Year 2: K=23.7, H=23.5, J=23.8 Year 2: K=23.7, H=23.5, J=23.8 (~120 hours) (~120 hours)

17. The UKIDSS Ultra-Deep Survey Depths achieved so far: ) (AB, 5 , 2" apertures) 0.88 deg. EDR: K=22.6, J=22.6 (~12 hours) (~12 hours) Year 1: K=23.5, J=23.6 (~85 hours) (~85 hours) Year 3: K=24.2, H=24.0, J=24.3 Year 3: K=24.2, H=24.0, J=24.3 (~250 hours) (~250 hours) Year 2: K=23.7, H=23.5, J=23.8 Year 2: K=23.7, H=23.5, J=23.8 (~120 hours) (~120 hours) Year 3 data becomes ESO public in July Year 3 data becomes ESO public in July

18. x20 x400 Unique depth+area in NIR plus strong + multi-wavelength coverage The UKIDSS Ultra-Deep Survey

19. The Subaru/XMM Deep Field RA = 02 18 00, Dec = -05 00 00 Optical Subaru: B=28.2, V=27.6, R=27.5, i’=27.2, z’=26.3 Optical CFHT: ugriz X-ray: XMM-Newton 100ks + 6x50ks Radio: VLA 12 μJy rms 1.4Ghz Spitzer: Spitzer SWIRE 3.6-160μm (NEW: Legacy survey) Submm: SHADES 8mJy (850μm) GALEX: FUV+NUV

20. The UKIDSS Ultra-Deep Survey

21. FUV+NUV+ugri+BVRi’z’+JHK+IRAC1+IRAC2  = 0.03 ~1% of outliers Importance of multiwavelength data : photometric redshifts Photometric redshifts are based on template fitting Currently using 16 broad-band filters: Currently ~3000 spectroscopic redshifts available Photometric redshifts by Michele Cirasoulo (Edinburgh) currently impossible to get spectra for > 100,000 objects (many more coming from FORS2/VIMOS +FMOS)

22. When are galaxies assembled? When are galaxies assembled? - detailed luminosity functions from 1<z<6 - detailed luminosity functions from 1<z<6 High-z galaxy mass function High-z galaxy mass function - Model SEDs ( GALEX+CFHT+SUBARU+UKIRT+SPITZER ) - Model SEDs ( GALEX+CFHT+SUBARU+UKIRT+SPITZER ) How do galaxy properties evolve with time? How do galaxy properties evolve with time? - Formation of the red sequence - Formation of the red sequence - Morphologies, prevalence of AGN, starformation rate - Morphologies, prevalence of AGN, starformation rate Large-scale structure Large-scale structure - provides probe of dark matter halos - provides probe of dark matter halos - evolution of clustering & bias - evolution of clustering & bias Key goals of the Ultra-Deep Survey

23. Science results from the UDS 1. Galaxy colour bimodality out to z~2 2. K-band luminosity function out to z~4 3. Obscured galaxy formation (sub-mm) 4. Massive galaxies at 4.5<z<6.5

24. Baldry et al. 2004 Early type Late type Well studied in the local Universe Visvanathan & Sandage 1977; Bower et al. 1992; Starteva et al. 2001; Baldry et al. 2004 The evolution of colour bimodality Cirasuolo et al. 2007

25. Bell et al. 2004 Combo-17 R < 24 Well studied in the local Universe Visvanathan & Sandage 1977; Bower et al. 1992; Starteva et al. 2001; Baldry et al. 2004 Extended up to z  1 Bell et al. 2004; Willmer et al. 2005; Franzetti et al. 2006 The evolution of colour bimodality Cirasuolo et al. 2007

26. The evolution of colour bimodality Primary selection in K-band ⇒ No bias against red objects Red objects present at any redshift Strength of bimodality decreases with redshift Star formation Reddening Cirasuolo et al. 2007

27. Science results from the UDS 1. Galaxy colour bimodality out to z~2 2. K-band luminosity function out to z~4 3. Obscured galaxy formation (sub-mm) 4. Massive galaxies at 4.5<z<6.5

28. Evolution of the near-IR galaxy LF >50,000 galaxies with K AB ≤ 23 Local K-band LF Schechter function with Luminosity evolution + Density evolution Cirasuolo et al. 2008, arXiv:0804.3471

29. Comparison with some results in literature Caputi et al. 2006 Saracco et al. 2006 Pozzetti et al. 2003 Evolution of the near-IR galaxy LF Cirasuolo et al. 2008, arXiv:0804.3471

30. Comparison with theoretical models Bower 2006 De Lucia 2007 Monaco 2007 Menci 2006 Nagamine 2006 Evolution of the near-IR galaxy LF Cirasuolo et al. 2008, arXiv:0804.3471

31. Comparison with theoretical models Bower 2006 De Lucia 2007 Monaco 2007 Menci 2006 Nagamine 2006 Evolution of the near-IR galaxy LF Cirasuolo et al. 2008, arXiv:0804.3471 next data-release will push one magnitude deeper

32. Science results from the UDS 1. Galaxy colour bimodality out to z~2 2. K-band luminosity function out to z~4 3. Obscured galaxy formation (sub-mm) 4. Massive galaxies at 4.5<z<6.5

33. >60% of cosmic star formation history is obscured >60% of cosmic star formation history is obscured Hughes et al. (1998) Nature, 394, 241 Obscured galaxy formation

34. Galaxy spectrum at progressively higher redshifts A clear view from z = 1 to z = 8 (reionization?) Sub-mm astronomy: Obscured galaxy formation

35. UDS has been observed by SCUBA at 850μm and AzTEC at 1.1mm as part of SHADES Survey Obscured galaxy formation

36. Sometimes identification can be tricky e.g. SMA follow-up of SXDF850.6 Iono et al. (2008) VLA 1.4 GHzOptical - Subaru SMA

37. Finally …….unambiguous K-band ID SMA on optical SMA on K-band Demonstrates: 1.power of sub-mm interferometry 2.importance of near-IR data identification & study of host galaxy

38. S 850 > 6 mJy S 850 < 6 mJy Anti-hierarchical growth? Cirasuolo et al. 2008, in prep Currently analysing SCUBA+AzTEC sources in UDS+LOCKMAN to confirm result

39. Science results from the UDS 1. Galaxy colour bimodality out to z~2 2. K-band luminosity function out to z~4 3. Obscured galaxy formation (sub-mm) 4. Massive galaxies at 4.5<z<6.5

40. 40 Massive galaxies at 4.5<z<6.5 Selecting galaxies at high redshift Two basic techniques: 1. Lyman-break selection (LBGs) 2. Narrow-band selection of Lyman alpha emitters (LAEs) B V R i z J H K 3.6μm 4.5μm

41. 41 Massive galaxies at 4.5<z<6.5 Selecting galaxies at high redshift Two basic techniques: 1. Lyman-break selection (LBGs) 2. Narrow-band selection of Lyman alpha emitters (LAEs) B V R i z J H K 3.6μm 4.5μm z=5.5 BC model

42. 42 The depth and spatial resolution of the HST ACS imaging in the Ultra Deep Field and wider GOODS N+S fields has been crucial Has allowed high-redshift luminosity function be traced as faint as ~0.1 L* However: Very small areas (HUDF ~13 arcmin 2 ] Potential for large cosmic variance, particularly at bright-end of LF Massive galaxies at 4.5<z<6.5

43. 43 B-drops at z~4 V-drops at z~5 i-drops at z~6 Adapted from Bouwens et al. (2007) Massive galaxies at 4.5<z<6.5

44. 44 Small area of HST fields means there is virtually no information brighter than M* Massive galaxies at 4.5<z<6.5

45. McLure et al. 2008, arXiv:0805:1335 Strategy: Selected z<26 (AB) catalog from SXDS data (z=6.5 limit) Rejected anything formally detected in B-band image (4.5<z<6.5) Photometric redshift fitting for all candidates (~6000 objects) Used redshift probability function P(z) to construct V/V max LF estimate More inclusive than strict “drop-out” selection Maximizes available redshift information Massive galaxies at 4.5<z<6.5

46. 2. Wide area allows accurate clustering analysis: r o =8 Mpc, halo masses ~ 5x10 11 M  1. Clear evolution in UV LF from z=5 to z=6 : can’t be evolution in Φ ★ alone Seb Foucaud (Nottingham)

47. Massive galaxies at 4.5<z<6.5 How do we compare with previous studies?

48. Massive galaxies at 4.5<z<6.5 Excellent agreement with Bouwens et al. (2007) Surprising given: greatly differing areas, data & techniques

49. Massive galaxies at 4.5<z<6.5 ML fits to the combined ground+HST data-sets M* brightens by ~0.7 magnitudes from z=6 to z=5 No significant evolution of normalization or faint-end slope

50. Massive galaxies at 4.5<z<6.5 B V R i z J H K 3.6μm 4.5μm Stacking analysis: 5<z<6 LBG sample stacked data for ~750 5<z<6 LBGs z phot = 5.43 Av = 0.0 Age = 400 Myr Mass = 10 10.0 M  SWIRE data only

51. Massive galaxies at 4.5<z<6.5 +

52. + Bower De Lucia Combination of LF and typical M/L allows rough estimate of stellar mass function/density: Stellar mass in place by z~5 is ~1x10 7 M  Mpc -3 Stellar mass in place by z~6 is ~4x10 6 M  Mpc -3 (c.f. Yan et al. 2006; Stark et al. 2007)

53. Outline Understanding galaxy formation Understanding galaxy formation Why we need deep NIR surveys Why we need deep NIR surveys UKIDSS & the Ultra Deep Survey UKIDSS & the Ultra Deep Survey UDS science results (Edinburgh) UDS science results (Edinburgh) The future: UDSz + spUDS The future: UDSz + spUDS

54. Spitzer Legacy Programme: spUDS 124 hours IRAC 168 hours MIPS

55. Full field mosaic with IRAC 3.6,4.5,5.8,8.0 microns 5σ limit of 24.2(AB) at 3.6 microns (7 times deeper than current SWIRE coverage) Full field mosaic with MIPS 24 microns 5σ limit of 18.8(AB) (4 times deeper than current SWIRE coverage) Science drivers: 1. Reliable determination of galaxy masses at high-z 2. Separation of galaxy populations into passive/starforming Observations completed end of Feb 2008

56. Spitzer Legacy Programme: spUDS 124 hours IRAC 168 hours MIPS

57. IRAC+MIPS world data release in ~6 months

58. ESO Large Programme: UDSz 93 hours VIMOS 142 hours FORS2

59. n When are galaxies assembled? - detailed luminosity functions from 1<z<4 - detailed luminosity functions from 1<z<4 - high-z mass function - high-z mass function n Large-scale structure - evolution of clustering & bias - evolution of clustering & bias - halo occupation; how many galaxies per dark matter halo? - halo occupation; how many galaxies per dark matter halo? n How do galaxy properties evolve with time? - Formation of the red sequence - Formation of the red sequence - Influence of environment - Influence of environment n Legacy value Key goals of UDSz

60. 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 photo-z 8000 6000 4000 2000 0 count ESO Large Programme: UDSz K-selected sample to K AB 1 (plus control sample) Sampling 1/6 galaxies (~4000) K-selected sample to K AB 1 (plus control sample) Sampling 1/6 galaxies (~4000)

61. 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 photo-z 8000 6000 4000 2000 0 count ESO Large Programme: UDSz K-selected sample to K AB 1 (plus control sample) Sampling 1/6 galaxies (~4000) K-selected sample to K AB 1 (plus control sample) Sampling 1/6 galaxies (~4000) All galaxies observed in red +blue: VIMOS LR-Blue VIMOS LR-Red FORS2 300I

62. 8 VIMOS POINTINGS 20 FORS2 POINTINGS

63. Summary The UDS is already the deepest, wide-area NIR survey undertaken Excellent multi-wavelength coverage ideal for galaxy evolution studies All the Subaru optical and UKIRT-IR data is publicly available Large Spitzer legacy programme completed - public in 6 months time Large ESO spectroscopic programme on-going

66. Latest news …

67. An extremely faint quasar at z=6.01 2D GMOS spectrum (courtesy of Chris Willott) Object original identified in McLure et al. (2006) from SXDS plus UDS EDR data Classified as massive LBG at z phot =5.9+/-0.2 Faintest known quasar at z~6, M UV ~ -22 (4 magnitudes fainter than SDSS quasars) “Seyfert galaxy” at z=6

68. LAE at z=6.05 from FORS2

69. In the near future…

70. 20 22 24 26 28 z > 1 z < 1 I 5000 4000 3000 2000 1000 0 count

71. The size evolution of massive galaxies McLure et al. (2007, in prep] Recent studies ( e.g. Trujillo et al. 2006, Longhetti et al. 2007, Zirm et al. 2007) have concluded that massive galaxies at 1.5<z<2.5 are factor ~4 smaller than their local counterparts. Appears to rule out simple passive evolutionary history

72. The size evolution of massive galaxies McLure et al. (2007, in prep] Appears to rule out simple passive evolutionary history Power of the UKIDSS UDS is that we can now study size evolution of massive galaxies using complete samples of ~5000, M>10 11 M  objects Recent studies ( e.g. Trujillo et al. 2006, Longhetti et al. 2007, Zirm et al. 2007) have concluded that massive galaxies at 1.5<z<2.5 are factor ~4 smaller than their local counterparts.

73. The size evolution of massive galaxies McLure et al. (2007, in prep] Complete sample of 5000 M>10 11 M  galaxies in interval 0.0<z<2.5 Confirm massive galaxies at z~2 are smaller than locally, but by less than factor of two Suggests factor of 1.5-2.0 growth is needed since z~1.5 Fully consistent with on average one major merger in last 9 Gyrs

74. Why Deep IR surveys ? Better tracer of the mass in stars Less affected by dust extinction LVLV LKLK

75. Massive galaxies at z>5 Strategy: McLure et al., 2006, MNRAS, 372, 357 Exploit large area advantage over previous surveys (0.6 square degrees) Search confined to brightest LBGs at z>5, with z’<25(AB) Specific aims: Calculate number density of massive LBGs at z>5, with low cosmic variance Constrain high-mass end of galaxy mass function at 5<z<6 Compare with Λ CDM halo mass function Compare with latest galaxy mass function predictions

76. z’ 10  detections Non-detections in B and V-bands (2  ) R-z > 3 (ensures redshift z>5) Selection criteria: z=5.5, BC model Massive galaxies at z>5

77. Over 0.6 square degree area, 74 objects met initial selection criteria SED fitting of remaining candidates 65 objects excluded due to plausible low-redshift solutions (e.g. heavily reddened EROs at z~1, galactic M dwarf stars) Final sample consists of only 9 objects Completeness corrected surface density = 0.005 +/- 0.002 arcmin -2 c.f. HST deep fields surface density = 0.004 +/- 0.004 arcmin -2 (Bouwens et al. 2006) based on single object at z<25ext

78. z phot = 5.41 Av = 0.6 Age = 500 Myr Mass = 1.6 x10 11.0 M  Example SED fits z phot = 5.26 Av = 0.0 Age = 114 Myr Mass = 4 x 10 10.0 M 

79. STACKING ANALYSIS B R V z` i` J 3.6 K Average stack of all 9 LBG candidates, increases depth by ~ 1 magnitude Confirm non-detections in B and V-bands to limits of B=30.3, V=29.5 (1  )

80. STACKING ANALYSIS Average stack of LBG candidates has mass =10 10.7 M  Median stack of LBG candidates has mass = 10 11.0 M  SBM03#3 (Bunker et al. 2003)

81. Effective volume = 3.3x10 6 Mpc 3 Number density of objects with M>10 ^11 M  : log  Mpc -3 )= -5.2 Halo:stellar mass ratio = 15 Low redshift data from Caputi et al. (2006) study in GOODS (blue points) Approx ~ 1% of high-mass galaxies in place by z~5 Massive galaxies at z>5 Comparison with halo mass function: number density of massive galaxies in UDS fully consistent with available dark matter halos in concordance cosmology

82. Thick solid line shows z=0 galaxy mass function from Cole et al. (2001) Dotted and stepped curves show predicted z=5.3 galaxy mass functions from Granato et al. (2004) and Bower et al. (2006) models. UDS number density is in good agreement with model predictions Massive galaxies at z>5 Comparison with galaxy mass function: Good agreement with model predictions maintained even if LBG selection technique is missing ~50% of stellar mass (e.g. Stark et al. 2006) MF at z=0 (Cole 2001) Durham model (Bower 2006) Trieste model (Granato 2004)

83. 10 – 15 % of local massive galaxies in place before z~3 The assembling of 80% of massive galaxies occurs in the range 1 < z < 3 Local space density M CDM > 5  10 12 M  M CDM > 2 x 10 12 M  ∗ M * > 10 11 M  The most massive galaxies GOODS (Caputi et al. 2006) Cirasuolo et al. 2008, in prep

84. Combination of UDS EDR+SXDS data places constraints on the high-mass end of galaxy mass function in the redshift interval 5<z<6. Number density of M>10 ^11 M  galaxies is found to be : log  Mpc -3 )= -5.2 Number density is in good agreement with the latest predictions for both the halo and galaxy mass functions at z>5 Massive galaxies at z>5 Conclusions: Next stage of this study is to exploit the deeper UDS DR1 data-set to study the UV-selected luminosity function at z>4.5

85. The Universe at z>5 Bouwens et al. 2006

86. UV selected galaxy luminosity function at high-redshift Faint end of high-z LF well determined from deep HST fields Bouwens et al. (2007) B-drops at z~4 V-drops at z~5 i-drops at z~6 Iye et al. 2006 Vast majority are faint (z-band > 26) and therefore not massive systems M < 10 10 M 