Improved mock galaxy catalogs for the deep2 galaxy redshift survey from subhalo abundance and environment matching

We develop empirical methods for modeling the galaxy population and populating cosmological N-body simulations with mock galaxies according to the observed properties of galaxies in survey data. We use these techniques to produce a new set of mock catalogs for the DEEP2 Galaxy Redshift Survey based on the output of the high-resolution Bolshoi simulation, as well as two other simulations with different cosmological parameters, all of which we release for public use. The mock-catalog creation technique uses subhalo abundance matching to assign galaxy luminosities to simulated dark-matter halos. It then adds color information to the resulting mock galaxies in a manner that depends on the local galaxy density, in order to reproduce the measured color-environment relation in the data. In the course of constructing the catalogs, we test various models for including scatter in the relation between halo mass and galaxy luminosity, within the abundance-matching framework. We find that there is no constant-scatter model that can simultaneously reproduce both the luminosity function and the autocorrelation function of DEEP2. This result has implications for galaxy-formation theory, and it restricts the range of contexts in which the mock catalogs can be usefully applied. Nevertheless, careful comparisons show that our new mock catalogs accurately reproduce a wide range of the other properties of the DEEP2 catalog, suggesting that they can be used to gain a detailed understanding of various selection effects in DEEP2. © 2013. The American Astronomical Society. All rights reserved

Measuring the Growth of Structure with Spectroscopically Identified Groups and Clusters

Number counts of galaxy clusters offer a very promising probe of the Dark Energy (DE) equation-of-state parameter, $w$. The basic goal is to measure abundances of these objects as a function of redshift, compare this to a theoretical prediction, and infer the values of cosmological parameters. Various teams have proposed such a measurement, including the South Pole Telescope, the Dark Energy Survey and the Red-Sequence Cluster Survey. The specific study discussed here detects clusters and smaller galaxy groups in the three-dimensional distribution of galaxies inferred from a large spectroscopic redshift survey. This method allows the abundance, $N$, of groups and clusters to be measured as a function of \emph{velocity dispersion}, as well as of redshift, permitting a more sensitive test of cosmology

All-wavelength Extended Groth strip International Survey: the environment of X-ray sources at z~1

We explore the environment of z~1 AGN using a sample of 53 spectroscopically identified X-ray sources in the All-wavelength Extended Groth strip International Survey. We quantify the local density in the vicinity of an X-ray source by measuring the projected surface density of spectroscopically identified optical galaxies within a radius defined by the 3rd nearest neighbour. Our main result is that X-ray selected AGN at z~1 avoid underdense regions at the 99.89% confidence level. Moreover, although we find that the overall population shares the same (rich) environment with optical galaxies of similar U-B and M_B, there is also tentative evidence (96%) that AGN with blue colors (U-B<1) reside in denser environments compared to optical galaxies. We argue that the results above are a consequence of the whereabouts of massive galaxies, capable of hosting supermassive black holes at their centers, with available cold gas reservoirs, the fuel for AGN activity. At z~1 an increasing fraction of such systems are found in dense regions

The All-Wavelength Extended Groth Strip International Survey (AEGIS) data sets

In this the first of a series of Letters, we present a panchromatic data set in the Extended Groth Strip region of the sky. Our survey, the All-Wavelength Extended Groth Strip International Survey (AEGIS), aims to study the physical properties and evolutionary processes of galaxies at z ∼ 1. It includes the following deep, wide-field imaging data sets: Chandra/ACIS X-ray, GALEX ultraviolet, CFHT/MegaCam Legacy Survey optical, CFHT/CFH12K optical, Hubble Space Telescope/ACS optical and NICMOS near-infrared, Palomar/WIRC near-infrared, Spitzer/IRAC mid-infrared, Spitzer/MIPS far-infrared, and VLA radio continuum. In addition, this region of the sky has been targeted for extensive spectroscopy using the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II 10 m telescope. Our survey is compared to other large multiwavelength surveys in terms of depth and sky coverage. © 2007. The American Astronomical Sociey, All rights reserved