Can We Detect the Color-Density Relation with Photometric Redshifts?

Abstract

A variety of methods have been proposed to define and to quantify galaxy environments. While these techniques work well in general with spectroscopic redshift samples, their application to photometric redshift surveys remains uncertain. To investigate whether galaxy environments can be robustly measured with photo-z samples, we quantify how the density measured with the nearest neighbor approach is affected by photo-z uncertainties by using the Durham mock galaxy catalogs in which the 3D real-space environments and the properties of galaxies are exactly known. Furthermore, we present an optimization scheme in the choice of parameters used in the 2D projected measurements which yield the tightest correlation with respect to the 3D real-space environments. By adopting the optimized parameters in the density measurements, we show that the correlation between the 2D projected optimized density and real-space density can still be revealed, and the color-density relation is also visible out to $z\sim 0.8$ even for a photo-z uncertainty (${\sigma }_{{\Delta }_z/(1+z)}$) up to 0.06. We find that at the redshift $0.3<z<0.5$ a deep ($i\sim 25$) photometric redshift survey with ${\sigma }_{{\Delta }_z/(1+z)}=0.02$ yields a comparable performance of small-scale density measurement to a shallower $i\sim$ 22.5 spectroscopic sample with $\sim$ 10% sampling rate. Finally, we discuss the application of the local density measurements to the Pan-STARRS1 Medium Deep survey, one of the largest deep optical imaging surveys. Using data from $\sim 5$ square degrees of survey area, our results show that it is possible to measure local density and to probe the color-density relation with 3$\sigma$ confidence level out to $z\sim 0.8$ in the PS-MDS. The color-density relation, however, quickly degrades for data covering smaller areas.

ApJ accepted; 29 figures

References in corpus (14)

• EAZY: A Fast, Public Photometric Redshift Code
• zCOSMOS: A Large VLT/VIMOS redshift survey covering 0 < z < 3 in the COSMOS field
• Ram pressure stripping the hot gaseous halos of galaxies in groups and clusters
• The DEEP2 Galaxy Redshift Survey: The Relationship Between Galaxy Properties and Environment at z ~ 1
• The DEEP2 Galaxy Redshift Survey: Evolution of the Color-Density Relation at 0.4 < z < 1.35
• The effects of environment on morphological evolution between 0<z<1.2 in the COSMOS Survey
• Cosmic Web and Star Formation Activity in Galaxies at z~1
• The Pan-STARRS1 Medium-Deep Survey: The role of galaxy group environment in the star formation rate versus stellar mass relation and quiescent fraction out to $z\sim 0.8$
• Discovery of a large number of candidate proto-clusters traced by ~15 Mpc-scale galaxy overdensities in COSMOS
• The Different Environmental Dependencies of Star-formation for Giant and Dwarf Galaxies
• Measuring galaxy environments in large scale photometric surveys
• The SPLASH survey: Quiescent galaxies are more strongly clustered but are not necessarily located in high-density environments
• Reconstructing the galaxy density field with photometric redshifts: I. Methodology and validation on stellar mass functions
• Recovering the real-space correlation function from photometric redshift surveys

Cited by in corpus (11)

• Cosmic Web of Galaxies in the COSMOS Field: Public Catalog and Different Quenching for Centrals and Satellites
• The Effect of Filaments and Tendrils on the HI Content of Galaxies
• The Three Hundred Project: The influence of environment on simulated galaxy properties
• The Pan-STARRS1 Medium-deep Survey: Star Formation Quenching in Group and Cluster Environments
• Reconstructing the galaxy density field with photometric redshifts: II. Environment-dependent galaxy evolution since $z\simeq 3$
• A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). VII. Redshift Evolution of Radio Galaxy Environments at z=0.3-1.4
• More connected, more active: galaxy clusters and groups at z~1 and the connection between their quiescent galaxy fractions and large-scale environments
• Environmental Effects on AGN activity via Extinction-free Mid-Infrared Census
• Optically-detected galaxy cluster candidates in the $AKARI$ North Ecliptic Pole field based on photometric redshift from Subaru Hyper Suprime-Cam
• Measuring galaxy environment with the synergy of future photometric and spectroscopic surveys
• The effect of environment on the properties of the most massive galaxies at $0.5<z<2.5$ in the cosmos-dash field