Large-Scale Structure at z=1: Results from the DEEP2 Survey

Alison CoilSteward ObservatoryUniversity of Arizona

March 2006

Talk Overview

•DEEP2 Redshift Survey overview•Luminosity-dependence of Clustering at z=1•Galaxy Properties vs. Environment•Evolution of Blue Fraction in Groups•QSO-galaxy clustering

The DEEP2 Collaboration

U.C. BerkeleyM. Davis (PI) M. Davis (PI)

M. Cooper M. Cooper

B. Gerke B. Gerke

R. Yan R. Yan

C. ConroyC. Conroy

Steward Obs. A. Coil

U.C. Santa Cruz S. Faber (Co-PI)

D. Koo

P. Guhathakurta

D. Phillips

K. Noeske

A. Metevier

L. Lin

N. Konidaris

G. Graves

LBNL J. NewmanJ. Newman

Maryland B. Weiner

Virginia R. Schiavon

NOAO J. Lotz

The DEEP2 Galaxy Redshift Survey, which uses the DEIMOS spectrograph on the Keck II telescope, is studying

both galaxy properties and large-scale structure at z=1.

C. Willmer

Comparison with Other Surveys

1.00E+03

1.00E+04

1.00E+05

1.00E+06

1.00E+05 1.00E+06 1.00E+07 1.00E+08

Volume ( h -3 Mpc 3)

Number of Galaxies z~0z~1

DEEP2

SDSS

2dF

CFA+SSRS

LCRS

PSCZ

DEEP2 was designed to have comparable size and density to previous generation local redshift surveys and is

>50 times larger than previous intermediate surveys at z~0.3-1.

DEEP2 has a different geometry than local

surveys: 20x~80x1000 h-3 Mpc3 per field

few x smaller than 2dF>4x larger than VVDS

~2.5x COMBO-17

Vital Statistics of DEEP2

• 3 sq. degrees of sky• 4 fields (0.5o x <2o) - lower cosmic variance errors• primary z~0.7-1.4 (pre-selected using BRI photometry)• >40,000 redshifts• comoving volume: ~5·106 h-3 Mpc3

• 400 slitmasks over 80 Keck nights• One-hour exposures• RAB=24.1 limiting magnitude• 1200 l/mm: ~6500-9200 Å• 1.0” slit: FWHM 68 km/s - high-resolution

AEGIS: the All-wavelength Extended Groth Strip International Survey

Spitzer MIPS, IRACDEEP2 spectra and Ks imagingHST/ACSV,I (Cycle 13)

Background: 2 x 2 degfrom POSS

DEEP2/CFHTB,R,I

GALEX NUV+FUV

Chandra & XMM: Past coverage Awarded (1.4Ms)

VLA - 6cm (0.5 mJy) + 21cm (0.1 mJy)

SCUBA

AEGIS ApJ Letters in prep:

Conselice: Properties of Massive and Red GalaxiesFang: Chandra observations of DEEP2 groups

Georgakakis: Environments of Chandra sourcesGerke: A binary AGN at z=0.71

Huang: Mid-Infrared Spectroscopy of a very massive LBG at z=2.98Ivison: Deep radio imaging of EGS

Kirby: SEDs of faint galaxiesLe Floc'h: Hidden star formation associated with a bright X-ray source

Lin: SFR in close pairsMetevier: Tully-Fisher relation for z>=0.9 galaxies in EGS

Moustakas: Strong gravitational lensing in the EGS Nandra: Host galaxy colors and masses of X-ray selected AGN

Pierce: AGN host morphologiesWeiner: Extinction and Star Formation Rate Calibrations from Optical

Emission Lines

Evolution of Galaxy Morphology in EGSPoster by J. Lotz on changes in morphological

distribution of galaxies from z=1.2 to z=0.3 using ~2000 DEEP2 galaxies:

1. buildup of E/S0/Sa since z~12. red sequence is mostly disk galaxies at z~1 and

E/S0/Sa by z~0.33. merger fraction is less than 10% and constant

with z4. fraction of irregular galaxies decreases toward

low z5. most 24m sources are Sc/d/Irr

Redshift Distribution of Data: z~0.7-1.4

Status: -three-year survey-currently ~90% complete-finishing EGS this spring

Target galaxies to be at z>0.7 with B-R, R-I colors. The cuts are very successful! Only miss 3% of high-z objects (blue). Don’t apply color cut in the EGS.

Redshifts are precise (30 km/s) and have high confidence: OII doublet and Ca H+K abs. features

DEEP2 sees the same color bi-modality as SDSS, COMBO-17, etc. to z>1

red

blue

bright faint two distinct spectral types as well

Evolution of the Luminosity Function

Willmer et al, 2005 + Faber et al. 2005, ApJ

M* evolves by ~1.3 mags/z - brighter in

past for both red and blue galaxies!

Number density is ~constant for blue

and lower at z=1 for red galaxies.

Build-up of galaxies on the red sequence. The red population is

not just evolving passively!

Redshift Maps in 4 Fields: z=0.7-1.3

Cone diagram of 1/12 of the full DEEP2 sample

Luminosity-dependence of clusteringat z=1 in DEEP2 data

From a sample of 25,000 redshifts over 3 deg2 in 4 fields -

create volume-limited subsamples as a function of

luminosity.

Brighter samples are more clustered and have steeper

slopes on small scales -- preferentially found in groups

at z=1 -- sub-structure.

Coil et al. 2006, ApJ100 kpc/h 20 Mpc/h

Galaxy separation(Mpc/h)

wp(

r p) -

clu

ster

ing

ampl

itud

e

Deviations from a power-law at z=1

Similar deviations from a power-law that are seen at z=0.1.Generally interpreted as one-halo and two-halo terms.

Coil et al. 2006, ApJ

SDSS z=0.1 DEEP2 z=1

Measure one-halo and two-halo terms

Coil et al., ApJ 2005

Can measure the one-halo and two-halo terms directly with a group catalog! Compare with mock catalogs that use an HOD model + DM NFW profile and find a discrepancy on small scales - ?

Data Mock

Luminosity/scale-dependence of bias

From the observed bias can infer the dark matter halo masses that host these galaxies: M > 9 1011-3 1012 M/h

Have now measured the scale-dependence and

luminosity-dependence of galaxy bias at z=1!

Rise in bias on small scales reflects physics of

galaxy formation and radial profile of galaxies

in halos.

DEEP2 sample - large-scales: b =1.26 (0.04) - 1.54 (0.05)

Theoretical Modelling of (r)

Diamonds - DEEP2 resultsSolid line - theoretical modelDotted line - dark matter

Conroy, Wechsler and Kravtsov 2006, ApJ predict the luminosity-dependent (r) using dark matter simulations - identify halos and

subhalos, assign L using the observed LF and the dist. of

(sub)halo masses by matching number densities: get a simple

relation b/w L-Vmax of halo-reproduce DEEP2 results quite well! (incl. rise on small scales)

Implies that luminosity-dependence of clustering is

driven by mass of (sub)halos

Galaxy Properties and Environment We can measure the local density - i.e., the

“environment” of any given object - using the distance to the 3rd nearest neighbor DEEP2 galaxy.

Cooper et al. 2006, ApJ: astro-ph/0603177

blue color red

line

ar o

verd

ensi

ty

blue color red

log

over

dens

ity

DEEP2SDSS (Blanton et al. 2004)

Environment over the CMD

Basic trends from z~0 studies persist at z~1: e.g., the reddest and brightest galaxies are preferentially found in dense environments.

brighter

redder

SDSS, z~0.1 DEEP2, 0.75<z<1.05

Cooper et al. 2006, ApJ: astro-ph/0603177

Environment vs. Luminosity

However, unlike locally, red and blue galaxies have very similar trends of environment vs. luminosity at z~1.

Blue galaxies Red galaxies

brighter

dens

er

brighter

Cooper et al. 2006, ApJ: astro-ph/0603177

In other words…

There exists a population of bright, blue galaxies in dense regions that is present at z~1 but not today. Presumably, their star-formation has quenched and are now on the red sequence.

dens

er

brighter

Baby pictures of today’s RS galaxies?

ACS data in the EGS - bright blue galaxies at z~1

Finding groups in DEEP2

We find groups using the locations of galaxies in redshift space - no selection based on color, magnitude, etc. - just overdensity in the

galaxy distribution.

position

Uses of groups include:1. LSS/cosmology: N(,z)

constrains w2. Galaxy formation and

evolution: e.g., the Butcher-Oemler effect

First DEEP2 Group Catalog

Gerke et al. 2005, ApJ

We currently have group catalogs for all 4 fields

Color/environment trend is driven by group (not massive cluster) galaxies

log

over

dens

ity

blue red

After group and cluster galaxies are

removed

Mean & median trends

Cooper et al. 2006, ApJ: astro-ph/0603177

Do these trends evolve over time?

Sample definition is critical for a clean test of the Butcher-Oemler effect. Volume-limited samples, to diff. limiting mag, w/ and w/o passive evolution. Tested extensively in mock catalogs w/ and w/o evolution in them.

brighter

Gerke et al. 2006, in prep

Evolution of blue fraction in groups

The blue fraction is lower in groups than the field, but evolves more quickly, and appears to be converging w/ field at z~1.2. Suggests that galaxies in groups start quenching at z~1.5 or so.

increasing z

Gerke et al. 2006, in prep

SDSS QSOs in DEEP2 fields

Coil et al., ApJ submitted

36 SDSS + 16 DEEP2 spectroscopic QSOs in the DEEP2 fields between z=0.7-1.4:

Clustering of Galaxies around QSOs

Clustering of DEEP2 galaxies around SDSS QSOs at z=0.7-1.4.

Errors include Poisson errors + cosmic variance.

Why measure the cross-correlation? Divide by the clustering of DEEP2 galaxies around DEEP2 galaxies to get the bias of QSO hosts…

Coil et al., ApJ submitted

Relative bias of QSOs to DEEP2 galaxies

The relative bias is ~1 +/-0.2

Galaxies that host QSOs at z=1 have the same clustering properties (same halo mass) as typical DEEP2 galaxies.

Don’t have same clustering as red/early-type galaxies (2 result) --- see the same result using local environment/overdensity

Places constraints on theoretical and semi-analytic models of quasars (Hopkins, Croton, etc.)

Coil et al., ApJ submitted

Other DEEP2 Papers

•Clustering of Groups and Group Galaxies (Coil et al., ApJ)•Void Probability Function (Conroy et al., ApJ)•Merger rate (Lin et al., ApJ)•Satellite Galaxy Kinematics (Conroy et al., ApJ)•Environments in Deep Redshift Surveys (Cooper et al., ApJ)•Metallicities of DEEP2 Galaxies (Shapley et al., ApJ)•Evolution of Galaxy Morphologies (Lotz et al., submitted ApJ)•Ages/Zs of early-type galaxies (Schiavon et al., submitted ApJ)•K+A/post-starburst galaxies (Yan et al., in prep)•Evolution of fine structure constant (Newman et al., in prep)

Data Release 1 (DR1): http://deep.berkeley.edu/DR1 - 1st season’s data - 7,500 redshifts + spectra - ~20% of full dataset