large-scale structure at z=1: results from the deep2 survey alison coil steward observatory...
Post on 22-Dec-2015
214 views
TRANSCRIPT
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!
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
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
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