Early Results from the DEEP2 Redshift Survey Benjamin Weiner (UCO/Lick Observatory) and the DEEP collaboration

DEEP 2 Survey Team UC Berkeley: M. Davis, J. Newman, A. Coil, D. Madgwick, M. Cooper, B. Gerke, R. Yan, C. Conroy UC Santa Cruz: S. Faber, D. Koo, P. Guhathakurta, A. Phillips, C. Willmer, R. Schiavon, N. Konidaris Caltech: C. Steidel, R. Ellis, T.Treu, C. Conselice Others: N. Kaiser, G. Wirth, A. Connolly, D. Finkbeiner, G. Luppino, P. Eisenhardt

DEEP : two redshift surveys Deep Extragalactic Evolutionary Probe DEEP 1: redshift survey in fields with deep HST WFPC2 imaging Keck/LRIS, 625 galaxy redshifts in Groth Strip DEEP 2: large scale survey targeting galaxy properties and clustering at z ~ 1 Keck/DEIMOS, goal 50,000 galaxy redshifts

DEEP 2 : a redshift survey at z ~ 1 1 Hour Survey: 1 hour exposures 4 fields, 3.5 square degrees magnitude limit R(AB) < ,000 targets, 50,000 galaxy redshifts most at 0.7<z< Keck nights over 3 years 3 Hour Survey: deeper exposures red (elliptical) galaxies probable z>1.5 galaxies - redshift failures from 1HS

Redshift surveys: background Las Campanas Redshift Survey (Shectman et al 1996) Surveys probe distribution of galaxies Also provide samples to study galaxy properties

DEEP2 compared to low- z surveys

Studying galaxies at z=1 Universe half its current age, Galaxies are younger but still recognizable Spectral features accessible to optical telescopes HST IR/optical imaging corresponds to restframe red/blue from HST WFPC2 Groth Strip

DEEP2 target selection Galaxies selected from CFHT 12K imaging, R(AB)< fields, each 0.5 x 2.0 deg (Groth Strip 0.25 x 2.0 deg) Color- cut selection in 3 fields selects z>0.7 galaxies; in Groth Strip we take everything. 2- pass and 4- pass mask coverage 200” x 200” from BRI CFHT images

DEEP2 spectroscopy DEIMOS with line grating A, covers [O II] 3727 doublet at 0.7<z<1.5 Distinctive feature: high resolution 1.0” slit, resolution 1.5 A FWHM, [O II] well resolved 60 km/sec FW at z=1, dispersion  = 25 km/sec Can measure internal kinematics: rotation/dispersion, galaxy masses

DEIMOS spectrograph at Keck II Nasmyth focus

Inside DEIMOS

Spectra from DEIMOS: lots of slits! One-half of one mask. Each has slits, average 5” long

Reduced data through pipeline cleaned, combined, sky subtracted Pipeline developed from SDSS code (of Schlegel, Finkbeiner, Burles) by UC Berkeley group galaxy group,  ~ 250 km/sec, at z~1

Redshift measurement and verification Find candidate redshifts by automated chi-sq fit to a set of templates Need to be checked by humans: GUI shows 1- D and 2- D data

Progress so far Instrument working well, pipeline in operation Both in use by other Keck users 190/480 masks observed, 40% complete 8,200 galaxy redshifts checked and in catalog

Redshift, color and magnitude 2700 galaxies in Groth Strip Large scale structure walls Color bimodality - red/blue

Photo- z color cut Redshifts from Groth Strip verify color cut works cleanly

Redshift success and failure Most of failures are faint blue galaxies Most of these are presumably high z, z > 1.5

Space distribution z=0.4 z=1.3

Galaxy restframe color and luminosity Blue/red separation No faint red Brighter blue galaxies at high z Lose red galaxies to mag cutoff Extended Groth Strip

Galaxy restframe color and luminosity All fields: lots more galaxies at z>0.7 All fields (8000 galaxies)

Blue luminosity function Simplistic 1/Vmax on EGS data Evolution in blue galaxies at bright end? Real calculations forthcoming (Christopher Willmer et al)

Red galaxies are the ones with bulges DEEP 1 galaxies with HST imaging (fits by L. Simard) Blue galaxies: mostly exponential Red galaxies: more concentrated

Red bulges are bright at z < 1 DEEP 1 galaxies with HST imaging (fits by L. Simard) Blue galaxies: starforming, disky Red galaxies: brighter bulges

COMBO- 17 photometric survey Large area, 17 filters, photo- z Color evolution in red sequence Mass buildup in red galaxies? Bell et al. 2003

Color bimodality and evolution? L model Z model Which is consistent with color and luminosity evolution?

Galaxy correlation functions Alison Coil et al submitted Clustering measure quantified Red galaxies more clustered Starforming galaxies less clustered

Rotation curves Michael Cooper (UC Berkeley)

Integrated emission linewidths Fit lines to 1- D extracted spectrum Kinematic measurement even when spatially unresolved

Linewidth- magnitude relation 3200 galaxies, z > <z<0.8: slope same as low- z, ZP offset Higher redshifts: zeropoint offset increases slope flattens Bright galaxies with low dispersions

Color- magnitude relation At high z, bright galaxies had low dispersions relative to low z TF rel Yet bright galaxies are still redder - not pure starbursts Note selection limit in high z bin

Color- linewidth residual Pretty flat but for highest z bin Redder objects are brighter, and/or have lower dispersion than predicted from TF

[O II] line strength relations Equivalent width Absolute strength Both increase with redshift

[O II] luminosity function Simple 1/Vmax weighting Signature of evolution at bright end

Velocity function (baby steps) Like a luminosity function but counts number of objects of given dispersion Simple 1/Vmax weighting Suggestion of evolution at high mass end - fewer high dispersion galaxies at high redshift?

Where we're going Catching up to current data, and more data coming including Palomar K-band photometry More studies of galaxy properties and environment Galaxy groups Cosmological models and tests - counting halos, groups Confronting galaxy evolution models Extended Groth Strip - SIRTF, Galex, X- ray and radio data