Faint Red Galaxies

Evolved stars at High Redshift

May 28, 2003

P. J. McCarthy

UCSC

Carnegie Observatories

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

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 1989 10 sq .arcminutes

Hu & Ridgeway 1992

100 sq. arcminutes

Some EROs are Sub-mm sources

Dey et al. 1999

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 = 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

Reality Intrudes!

CIRSI + LCO Wide Field IR Camera

du Pont 2.5m telescope 4 1024 x 1024 arrays

cryogenic Offner relay 16 channel electronics

4 1024x1024 detectors – 90% gaps

4 pointings – 16 1024 x 1024 images

4 pointings – 16 1024 x 1024 images

4 pointings – 16 1024 x 1024 images

13’ x 13’ mosaic – 3 hour exposure

100,000

1024 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 < 1.0

1.0 < z < 1.5

1.5 < z < 2.0

2700 sq. arcmin

Classical Star Counts

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 DiagnosticsV 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. 2002

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 r0

All I-K K > 19 <z> 0.7

I-K > 4 19 < K < 20 <z> 1.0

I-K > 4 18 < K < 19 <z> 1.0

’’ I-K > 5 18 < K < 20 <z> 1.2

Generalized Limber equation:

n(z) for I-K selected subsamples

Inversion of to r0

All I-K K > 19 <z> 0.7 5 h-1Mpc

I-K > 4 19 < K < 20 <z> 1.0 9

I-K > 4 18 < K < 19 <z> 1.0 9

’’ I-K > 5 18 < K < 20 <z> 1.2 10

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 Galaxies4.0 < I – K < 4.5 <z> = 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 < I – K < 5.0 <z> = 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

AB

Typically A=60s/15 cy: 1800s exposure10 subtraction

GMOS N&S Sky residualsSUMMED 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=60sB=60s

+ 25s o/head

Gemini + GMOS

GMOS spectrographGemini

GMOSLRISLDSS1

GMOS on Gemini North

5’ x 5’ FOV R ~ 800

GDDS Spectra77 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

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

The Reddest Galaxies

The Reddest Galaxies

Glazebrook et al in prep

Color Evolution

Photometric Redshifts Spectroscopic 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