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

Distant Galaxy Studies in the 20 th 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

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

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 !

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!

Earliest IR Surveys – New Red population Elston, Rieke & Rieke sq.arcminutes Hu & Ridgeway sq. arcminutes

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

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

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

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 GOALS

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

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

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

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

4 1024x1024 detectors – 90% gaps

4 pointings – x 1024 images

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

Red Galaxies are Abundant V,I,K 80”

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

Photometric Redshifts from LCIR Chen et al 2002

Photometric Redshifts from LCIR Recent update GMOS redshifts

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

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

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

Color-Magnitude Diagram Stars 0.0 < z < < z < < z < sq. arcmin

Classical Star Counts

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

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

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

Color-Color Diagrams Stars form distinct sequence K < 17.5

Color-Color Diagrams Stars form distinct sequence K < 18.5

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

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

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

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

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

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

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

Angular vs. 3-D Clustering

Clustering of Red Galaxies

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

Angular Clustering  = 12” I – K > 4  = 1” All K < 20.5

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

Inversion of  to r 0  All I-K K >  I-K >  I-K >  ’’ I-K > Generalized Limber equation:

n(z) for I-K selected subsamples

Inversion of  to r 0  All I-K K > h -1 Mpc  I-K >  I-K >  ’’ I-K > Generalized Limber equation:

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

Evolution and Color Dependence Kauffmann et al 99 Early types Star forming galaxies LCRS CNOC2 CFRS CFGRS LBG

Morphology: What type of Galaxy are we talking about after all?

E/S0 Template Match Giavalisco et al Cycle 11 Treasury Program 10/5/02 public release 91 objects

Giavalisco et al Cycle 11 Treasury Program 10/5/02 public release Sab/Sbc Template Match

Giavalisco et al Cycle 11 Treasury Program 10/5/02 public release 54 objects E/S0 Template Match

Giavalisco et al Cycle 11 Treasury Program 10/5/02 public release Sab/Sbc Template Match

Morphologies of Red Galaxies 4.0 = 1.0 Template type 1 (E/S0) 85% Compact 10% Disks 5% Diffuse Template type 2 (Sab/Sbc) 60% Compact 35% Disks 5% Diffuse Template type 1 (E/S0) 60% Compact 25% Disks 15% Diffuse Template type 2 (Sab/Sbc) 40% Compact 30% Disks 30% Diffuse 4.5 = 1.2 See Stiavelli & Treu 1999 NICMOS results See Yan & Thompson 2002 WFPC2 results

Spectroscopy: Real redshifts and Spectral Diagnostics

Conventional Slit Spectroscopy Sky subtraction is primary limitation –Slit irregularities –Flat-field errors –Residual Fringing –Geometric distortions –Low slit density on sky Beam switching ? –Variable sky spectrum –Read noise penalty –High read-out overhead The solution: ‘nod & shuffle’ Glazebrook & Bland-Hawthorn 99

Sky cancellation: ‘nod and shuffle’ Storage of ‘sky’ image next to object image via ‘charge shuffling’ Zero extra noise introduced, rapid switching (60s) A B ABAB Typically A=60s/15 cy: 1800s exposure  10  subtraction

GMOS N&S Sky residuals SUMMED along long slit (1.8 arcmin) Raw Sky/20 Subtracted sky (i.e. ~10  level is enough for 200,000 sec pointed obs.) Cycle: A=60s B=60s + 25s o/head

Gemini + GMOS GMOS spectrograph Gemini GMOS LRIS LDSS1 GMOS on Gemini North 5’ x 5’ FOV R ~ 800

GDDS Spectra 77 objects 40,000 secs

[OII] Redshifts from GDDS 23.7 < I(AB) < 24.2

Absorption Line Spectra I = 24.0 Z = 1.67 I = 23.7 Z = 1.56 I = 24.2 Z = 1.39 Rest Wavelength

Interstellar Matter at z = 1.5 Red: Local Star burst composite (Tremonti et al.) Black: GDDS z = 1.5 I ~ 24.5 I-K < 3 composite

Interstellar Matter at z = 1.5

Gas Rich! DLAs Savaglio et al. 2003

K + A Galaxies Only 1 in 10,000 galaxies in LCRS have similar EWs

K + A Galaxies >45% burst by mass with 500My age ~5% of red galaxies are in this class!

The Reddest Galaxies

Glazebrook et al in prep

Color Evolution Photometric RedshiftsSpectroscopic Redshifts

Color Evolution Redshift desert is nearly gone……

Conclusions Counts: little density evolution to z ~ 1.2 LFs: R-band Luminosity density declines by < x 2 to z ~ 1.5 UV colors: wide range of star formation levels Clustering: Strong clustering consistent with local E population Morphologies: Predominantly early types Spectroscopy: Old & Intermediate age populations The Progenitors of Early Type Galaxies

Conclusions Population of massive field early types largely unevolved since z ~ 1.5 The Future ACS imaging of the GDDS Fields IMACS with its 27’ x 27’ and Nod & Shuffle with > 1000 slits per mask: Large Scale Structure at z ~ 1.5