The Environment on few Mpc scales of Infrared Luminous Galaxies at Redshifts z~1

TL;DR

This study examines the environments of infrared luminous galaxies at redshifts around 1, revealing their preference for denser regions and their significant role in galaxy evolution and star formation activity.

Contribution

It provides a detailed analysis of the environment of IR luminous galaxies at z~1, showing their intermediate density habitats and their association with galaxy groups, using MIPS and DEEP2 data.

Findings

IR luminous galaxies inhabit denser environments than average galaxies at similar redshifts.

Approximately 30% of IR luminous galaxies are in groups with substantial dark matter halos.

IR galaxies contribute significantly to the star formation rate density at z~1.

Abstract

We investigate the environment of infrared luminous galaxies (L$_{IR}$[8-1000 $\mu $m$] >10^{11}$L$_{\sun}$). We focus on the redshift range 0.7 $\leq$ z $\leq$ 1, where these galaxies dominate the star formation activity and play a significant role in galaxy evolution. We employ MIPS 24$\mu$m data to identify infrared galaxies in the Extended Groth Strip (EGS). We use a local density indicator to probe the environment on few Mpc scales and a group member catalog, both of which make use of the DEEP2 spectroscopic redshift catalog, to quantify the environment of these galaxies. We find that the local environment of LIRGs and ULIRGs is intermediate between that of blue and red galaxies. LIRGs and ULIRGs avoid underdense environments and inhabit local environments that are more dense on average than those of other DEEP2 galaxies at similar redshifts. However, when the comparison sample of the non-IR DEEP2 galaxies is restricted to have the same range of stellar mass, color, or luminosity as the IR--galaxies, there is no longer any significant difference in environment; the IR-galaxies follow the same trends in the color-environment and luminosity-environment relations observed at z$\sim$1. We also find that about 30% of the LIRGs and ULIRGs belong to groups, associated with a minimum dark matter halo of 6$\times10^{12}$M$_{\odot}$h$^{-1}$. The group members constitute 20 % of the sources responsible for the IR star formation rate density and comoving energy density at z$\sim$1.