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

Large-Scale Structure at z=1: Results from the DEEP2 Survey. Alison Coil Steward Observatory University 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

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

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  1. Large-Scale Structure at z=1: Results from the DEEP2 Survey Alison Coil Steward Observatory University of Arizona March 2006

  2. 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

  3. 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. The DEEP2 Collaboration 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. Newman Maryland B. Weiner Virginia R. Schiavon NOAO J. Lotz U.C. Berkeley M. Davis (PI) M. Cooper B. Gerke R. Yan C. Conroy Steward Obs. A. Coil C. Willmer

  4. Comparison with Other Surveys 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 SDSS 2dF LCRS DEEP2 CFA+ SSRS z~0 z~1 PSCZ

  5. 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-3Mpc3 • 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

  6. DEEP2/CFHT B,R,I GALEX NUV+FUV Chandra & XMM: Past coverage Awarded (1.4Ms) AEGIS: the All-wavelength Extended Groth Strip International Survey Spitzer MIPS, IRAC Background: 2 x 2 deg from POSS DEEP2 spectra and Ks imaging HST/ACS V,I (Cycle 13) VLA - 6cm (0.5 mJy) + 21cm (0.1 mJy) SCUBA

  7. AEGIS ApJ Letters in prep: Conselice: Properties of Massive and Red Galaxies Fang: Chandra observations of DEEP2 groups Georgakakis: Environments of Chandra sources Gerke: A binary AGN at z=0.71 Huang: Mid-Infrared Spectroscopy of a very massive LBG at z=2.98 Ivison: Deep radio imaging of EGS Kirby: SEDs of faint galaxies Le Floc'h: Hidden star formation associated with a bright X-ray source Lin: SFR in close pairs Metevier: 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 morphologies Weiner: Extinction and Star Formation Rate Calibrations from Optical Emission Lines

  8. Evolution of Galaxy Morphology in EGS Poster by J. Lotz on changes in morphological distribution of galaxies from z=1.2 to z=0.3 using ~2000 DEEP2 galaxies: buildup of E/S0/Sa since z~1 red sequence is mostly disk galaxies at z~1 and E/S0/Sa by z~0.3 merger fraction is less than 10% and constant with z fraction of irregular galaxies decreases toward low z most 24mm sources are Sc/d/Irr

  9. Redshift Distribution of Data: z~0.7-1.4 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 Status: -three-year survey -currently ~90% complete -finishing EGS this spring

  10. 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

  11. Evolution of the Luminosity Function 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! Willmer et al, 2005 + Faberet al. 2005, ApJ

  12. Redshift Maps in 4 Fields: z=0.7-1.3 Cone diagram of 1/12 of the full DEEP2 sample

  13. 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. wp(rp) - clustering amplitude Galaxy separation (Mpc/h) 100 kpc/h 20 Mpc/h Coilet al. 2006, ApJ

  14. Deviations from a power-law at z=1 SDSS z=0.1 DEEP2 z=1 Similar deviations from a power-law that are seen at z=0.1. Generally interpreted as one-halo and two-halo terms. Coilet al. 2006, ApJ

  15. Measure one-halo and two-halo terms Data Mock 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 - ? Coil et al., ApJ 2005

  16. Luminosity/scale-dependence of bias 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) From the observed bias can infer the dark matter halo masses that host these galaxies: M > 9 1011-3 1012 Mo/h

  17. Theoretical Modelling of x(r) • Conroy, Wechsler and Kravtsov 2006, ApJ predict the luminosity-dependent x(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 Diamonds - DEEP2 results Solid line - theoretical model Dotted line - dark matter

  18. We can measure the local density - i.e., the “environment” of any given object - using the distance to the 3rd nearest neighbor DEEP2 galaxy. SDSS (Blanton et al. 2004) DEEP2 Galaxy Properties and Environment log overdensity linear overdensity bluecolorred bluecolorred Cooper et al. 2006, ApJ: astro-ph/0603177

  19. Basic trends from z~0 studies persist at z~1: e.g., the reddest and brightest galaxies are preferentially found in dense environments. Environment over the CMD SDSS, z~0.1 DEEP2, 0.75<z<1.05 redder brighter Cooper et al. 2006, ApJ: astro-ph/0603177

  20. However, unlike locally, red and blue galaxies have very similar trends of environment vs. luminosity at z~1. Environment vs. Luminosity Blue galaxies Red galaxies denser brighter brighter Cooper et al. 2006, ApJ: astro-ph/0603177

  21. 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. In other words… denser brighter

  22. Baby pictures of today’s RS galaxies? ACS data in the EGS - bright blue galaxies at z~1

  23. position l 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. Uses of groups include: LSS/cosmology: N(s,z) constrains w Galaxy formation and evolution: e.g., the Butcher-Oemler effect

  24. First DEEP2 Group Catalog We currently have group catalogs for all 4 fields Gerke et al.2005, ApJ

  25. Color/environment trend is driven by group (not massive cluster) galaxies Mean & median trends log overdensity After group and cluster galaxies are removed bluered Cooper et al. 2006, ApJ: astro-ph/0603177

  26. 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

  27. Evolution of blue fraction in groups increasing z 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. Gerke et al. 2006, in prep

  28. SDSS QSOs in DEEP2 fields 36 SDSS + 16 DEEP2 spectroscopic QSOs in the DEEP2 fields between z=0.7-1.4: Coil et al., ApJ submitted

  29. 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

  30. 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 (2s 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

  31. 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

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