faint red galaxies evolved stars at high redshift nov 6, 2002 p. j. mccarthy stsci carnegie...

Faint Red Galaxies

Evolved stars at High Redshift

Nov 6, 2002

P. J. McCarthy

STScI

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

Steidel et al 99

Lilly, Madau

Distant Galaxy Studies in the 20th Century

• Probes galaxy building via star formation• Insensitive to assembly of galaxies via mergers• Selects by light not mass• Near-IR offers a window on mass evolution

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?

Elston, Rieke & Rieke 1989 10 sq .arcminutes

Z ~ 1 early types

Hu & Ridgeway 1992

100 sq. arcminutes

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• 0.5 square degrees J & K in hand• ~10,000 K-selected objects• ~70,000 photometric redshifts• 250 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

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 Connolly et al 1995,1997

Photometric Redshifts from LCIR

Chen et al 2002


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

Color-Magnitude Diagram

Stars

0.0 < z < 1.0

1.0 < z < 1.5

1.5 < z < 2.0

700 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 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



K < 18.5



• Z > 1 galaxies appear at K ~ 19

K < 19.5




• Z > 1.5 galaxies at K ~ 20

K < 20.8




• Z > 1.5 galaxies at K ~ 20

• Reddest galaxies follow minimal evolution track

K < 20.8

Color-Redshift Diagrams

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,Marzke 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


Sab/Sbc

Template

Match

Giavalisco

et al

Cycle 11

Treasury

Program


54 objects

E/S0

Template

Match

Giavalisco

et al

Cycle 11

Treasury

Program


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)


Template type 1 (E/S0)


Template type 2 (Sab/Sbc)


4.5 < I – K < 5.0 <z> = 1.2

See Stiavelli

& Treu 1999

NICMOS results

Spectroscopy:

Real redshifts and Spectral Diagnostics

Goals:• First Complete sample 1<z<2

– use photo-z’s to weed out low-z galaxies (BVRIzJHK)

• Determine luminosity and mass functions– Can we see the assembly of mass? – Massive galaxies at z=2 would severely trouble CDM– Mass(z) more robust than SFR(z)

• Relate to galaxy morphology (ACS)– Identify Ell/Sp/Irr over 1<z<2– Track low-z behavior to high-z

• E.g. can we see mass assembly of giant Ellipticals?• Can we track the dynamical evolution of spiral disks

• Track SFH over 1<z<2: – Age of galaxies, metallicities of population

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

Tel.+instr. efficiency

GMOS represents the best possible option for a red sensitive MOS. Ideal system for nod & shuffle

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

High Redshift Elliptical Galaxies?

FeIIMgII

53W091 at z=1.393VI=2.2 IK=2.94

Model: 4 Gyr old stellar populationat z=1.4, age of Universe = 4.5Gyr

z(form) ≈10

Obj # 398 from GDDS SA22VI=1.7 IK=2.7

Wavelength / Angstroms

f

Rest-frame UV absorption line redshifts!

Color-z of GDDS galaxies

At least halfway across the desert!!

Again just the easy ones…

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: Intermediate age populations

The Progenitors of Early Type Galaxies

Conclusions

Population of massive field early types largely unevolved since z ~ 1.5

The Future

Bridging the gap between the faint red galaxies at z ~ 1.5

and the LBGs at z > 2

Gemini Deep Deep Survey

GDDS Team: Karl Glazebrook (JHU), Bob Abraham (Toronto), Pat McCarthy (OCIW), Rick Murowinski (DAO), Ray Carlberg (Toronto), Ron Marzke (SDSU), Sandra Savaglio (JHU), H-W Chen (OCIW) David Crampton (DAO), Isobel Hook (Oxford), Inger Jørgensen & Kathy Roth (Gemini)

Goal: Deep 100,000 sec MOS exposures on Las Campanas IR Survey fields to get redshifts of a complete K<22.4 I<25 sample covering 1<z<2

GDDS history• Sep 2001: start of GDDS evil planning• Jan 2002: team approached Gemini observatory with nod

& shuffle proposal• Feb 2002, obtained Gemini go-ahead.• Feb-May 2002. Implementation of N&S at DAO (~$10K

cost)• May 2002: first N&S engineering observations on 8m• July 2002: N&S commissioned on sky• Aug 2002: First 4 nights of GDDS Science Verification

for N&S success!!• Sep-Dec 2002: Band I queue time, 50 hrs

GDDS mask84 objects 2 tiers with150 l/mm grating

GDDS Nod&Shuffle Mask

I=23.8

Example object: raw object+skyOH forest

I=23.8 z=1.07

Example object: N&S subtracted[OII] 3727at 7700Å

GDDS: Oct 2002 snapshot• GDDS SV Aug 2002 + Band I Queue time

(Sep/Oct 2002) Up to 100 ksec on first field (SA22)First 40 ksec now reduced and very preliminary redshifts

• TO COME 2002-2003 (total time awarded 50 hrs in Band I):Complete 3 GDDS fields, secure 100 z>1 redshifts

GDDS: ultra-super-preliminary results

These are just the‘easy’ ones so far!~ 40 ksec

Working on CCF

Data on this field is still coming in.

Full 100,000 secswill pound on z=1.5old red galaxies

High Redshift Elliptical Galaxies?

FeIIMgII

53W091 at z=1.393VI=2.2 IK=2.94

Model: 4 Gyr old stellar populationat z=1.4, age of Universe = 4.5Gyr

z(form) ≈10

Obj # 398 from GDDS SA22VI=1.7 IK=2.7

Wavelength / Angstroms

f

Rest-frame UV absorption line redshifts!

Colors of GDDS galaxies

GDDS

HDF LBGs (Papovich et al. 2001)

z=1.4 E/S0 template

z=1.4 Sbc template

Color-z of GDDS galaxies

At least halfway across the desert!!

Again just the easy ones…

GDDS: summary• GDDS hits complete sample at z>1

– Photo-z selection z>1 ~works

• Gets spectra via ‘nod & shuffle’ sky cancellation– Successfully commissioned July-Aug 2002, have data

on first (half) field

• Are we seeing a dearth of high mass galaxies at z>1 ? Possible epoch of mass assembly?

• TO COME 2002-2003:Complete 3 GDDS fields, secure 100 redshifts Apply for HST/ACS imaging for morphologies

Mass function vs Morphology vs z.

GDDS: seeking old

galaxies at z>1

z=1.4, IK=2.7

Obscured Charge

Storage Area

Obscured Charge Storage Area

First Exposure

Active slit area

“A” position

“B” position

Now nod telescope and shuffle charge

Nod & shuffle the other way

“A” position

“B” position

Repeat N times and then readout

Difference of two positions

Finally shift and add both

LBL High Resistivity CCDs


No fringing, but high CR rates


Straight average - 2 hours Nod & Shuffle


+/- 200 DN rejection


• Goal: Empirical understanding of early galaxy evolution

• Target: 1 square degree to K = 21

• Pilot survey in 2000/2001: VRIH to H=20.5

• Six fields around the equator (2 in south!)

• 1 square degree in BVRIz’H

• 0.5 square degrees in J & K to K = 20.8

• 200+ redshifts with LDSS2

• ~ 50 redshifts with GMOS & LRIS

Another example


McCarthy, Persson, Martini, Koviak (OCIW)

Chen (MIT), Marzke(SFSU), Carlberg, Abraham(UT)

Ellis (Caltech)

ConclusionsWe have identified a population having:

The colors and luminosities expected of evolved stellar systems

The space density & LF of early-type galaxies

Clustering scale lengths similar to present day massive galaxies

Morphologies that are primarily compact consistent with spheroid dominated systems

Spectral features indicative of turn-off ages > 1 Gyr

These are the progenitors of Elliptical Galaxies

faint red galaxies evolved stars at high redshift nov 6, 2002 p. j. mccarthy stsci carnegie...

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