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Faint Red Galaxies

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  1. Faint Red Galaxies Evolved stars at High Redshift P. J. McCarthy Carnegie Observatories UCSC May 28, 2003

  2. Distant Galaxy Studies in the 20th Century • Focused on faint blue galaxies • Samples UV bright populations • Traces heavy element production • Global census of conversion of gas into stars Evolution of UV luminosity density Madau et al Steidel et al 99

  3. Faint Galaxies in the Near Infrared • Sensitive to assembly of galaxies via mergers • Near-IR offers a window on mass evolution • Dust not (as) important Build-up of stellar mass over cosmic time Near-IR luminosity provides proxy for stellar mass Near IR-surveys are technically challenging

  4. Optical and near-IR Detectors Large formats: 2k x 4k 3 edge buttable 100 Mpixel FPAs common Cheap - $ 0.01 per pixel 2k x 2k maximum Non-buttable Expensive $ 0.13 per pixel !

  5. Challenges facing Deep near-IR Surveys • Detectors small and Expensive • Cryogenic Optics & baffles required • Sky 3 orders of magnitude brighter! • Can’t observe when the moon is down!

  6. Earliest IR Surveys – New Red population Elston, Rieke & Rieke 1989 10 sq .arcminutes Hu & Ridgeway 1992 100 sq. arcminutes

  7. Some EROs are Sub-mm sources Dey et al. 1999 Smail et al. 1999

  8. Two Red populations? Moderately red, high surface density on sky Z ~ 1 early types Extreme red colors, very rare Z > 1 Starbursts

  9. Las Campanas IR Survey PHASE I: A Carnegie-Cambridge-Toronto Collaboration PHASE II: A Diversified Conglomerate McCarthy, Persson, Martini, Koviak (OCIW) Chen (MIT), Marzke(SFSU), Carlberg, Abraham(UT) Ellis (Caltech), Firth, McMahon, Lahav (IoA)

  10. GOALS • Galaxy Assembly in the 1 < z < 2 Epoch • Space density of massive galaxies • Stellar evolution in early type galaxies • Evolution of 3-D Clustering • Growth of massive galaxies and structure

  11. Why Select in the near-IR? Z = 1.5 V I H K • Selects on basis of population with high M/L • Optical-IR color indices excellent for foreground rejection • That where the light is!

  12. Approach • Multi-color optical & near-IR imaging survey • Depths keyed to z = 2 elliptical: Ks ~ 21 ! • Photometric redshifts • Six fields around the celestial sphere • 1 square degree Color-Mag Diagrams Color-Redshift Diagrams Number Counts Color-Color Diagrams Luminosity Functions Angular Clustering Morphologies Spectroscopy

  13. Reality Intrudes! • Phase I: 1 square degree to H = 20.5 + VRI • Phase II: 1 square degree to K = 20.8 + BVRIz’JH • VRIH survey completed in spring 2001 • 0.75 square degrees J & K in hand • ~10,000 K-selected objects • ~70,000 photometric redshifts • ~ 350 spectroscopic redshifts

  14. CIRSI + LCO Wide Field IR Camera du Pont 2.5m telescope 4 1024 x 1024 arrays cryogenic Offner relay 16 channel electronics

  15. 4 1024x1024 detectors – 90% gaps

  16. 4 pointings – 16 1024 x 1024 images

  17. 4 pointings – 16 1024 x 1024 images

  18. 4 pointings – 16 1024 x 1024 images

  19. 100,000 1024 x 1024 Frames - 30 seconds each 13’ x 13’ mosaic – 3 hour exposure

  20. Red Galaxies are Abundant V,I,K 80”

  21. Photometric Redshifts • 8 color photometery BVRIz’JHKs • 6 Galaxy templates • 1 AGN, 128 stellar templates See Koo 1985 Connolly et al 1995,1997 Best fit template and redshift Likelihood function

  22. Photometric Redshifts from LCIR Chen et al 2002

  23. Photometric Redshifts from LCIR Recent update GMOS redshifts

  24. Basic Phenomenology: Sky density, Space Density, Luminosity & Color Evolution

  25. IR to Optical Color Selection I-K > 4 Rejects z < 1 Foreground & late types at all redshifts

  26. IR to Optical Color Selection I-K > 4 Rejects z < 1 Foreground & late types at all redshifts

  27. Color-Magnitude Diagram Stars 0.0 < z < 1.0 1.0 < z < 1.5 1.5 < z < 2.0 2700 sq. arcmin

  28. Classical Star Counts

  29. Classical Star Counts

  30. Number-Magnitude Relations I-K > 4.0 I-K > 4.5 I-K > 5.0

  31. Number-Magnitude Relations I-K > 4.0 I-K > 4.5 I-K > 5.0 Gardner et al K-band LF

  32. UV & Optical Color Diagnostics Z = 1.5 V I H K Optical to IR color sensitive to old population I-K Rest-frame UV slope sensitive to recent star formation V-I

  33. Color-Color Diagrams • Stars form distinct sequence K < 17.5

  34. Color-Color Diagrams • Stars form distinct sequence K < 18.5

  35. Color-Color Diagrams • Stars form distinct sequence • Z > 1 galaxies appear at K ~ 19 K < 19.5

  36. Color-Color Diagrams • Stars form distinct sequence • Z > 1 galaxies appear at K ~ 19 • Z > 1.5 galaxies at K ~ 20 K < 20.8

  37. Color-Color Diagrams • Stars form distinct sequence • Z > 1 galaxies appear at K ~ 19 • Z > 1.5 galaxies at K ~ 20 • Reddest galaxies follow minimal evolution track K < 20.8

  38. Evolving Luminosity Functions Luminosity functions from photometric redshifts Redshift errors must be explicitly treated! Chen et al. 2002

  39. Evolving Luminosity Functions • LFs derived from photo-z’s with modified likelihood approach • LF at intermediate z agrees well with CNOC2 • Very little apparent evolution in L* to z ~ 1.2 Chen et al. 2002

  40. R-band Luminosity Density Rest-Frame R-band Luminosity density little or no evolution to z ~ 1.2

  41. Clustering: A proxy for merging Tags populations at high and low redshift

  42. Angular vs. 3-D Clustering

  43. Clustering of Red Galaxies

  44. Angular Clustering Clustering amplitude of red galaxies is 20 x that of the full field

  45. Angular Clustering q = 12” I – K > 4 q = 1” All K < 20.5

  46. Angular Clustering • Clustering amplitude higher for redder colors and brighter magnitudes. • = 30” K ~ 18 & I-K > 5 n(z) required for r_0

  47. Inversion of w(q) to r0 Generalized Limber equation: q = 2 All I-K K > 19 <z> 0.7 q = 5 I-K > 4 19 < K < 20 <z> 1.0 q = 15 I-K > 4 18 < K < 19 <z> 1.0 q = 10’’ I-K > 5 18 < K < 20 <z> 1.2

  48. n(z) for I-K selected subsamples

  49. Inversion of w(q) to r0 Generalized Limber equation: q = 2 All I-K K > 19 <z> 0.7 5 h-1Mpc q = 5 I-K > 4 19 < K < 20 <z> 1.0 9 q = 15 I-K > 4 18 < K < 19 <z> 1.0 9 q = 10’’ I-K > 5 18 < K < 20 <z> 1.2 10

  50. Evolution and Color Dependence Red color selection or E morphological selection Blue color selection or late type morphological selection LCRS CNOC2 CFRS CFGRS LBG