The environment of radio sources in the VLA-COSMOS Survey field

TL;DR

This study investigates how the density of the environment influences the presence of radio AGNs up to redshift 2, revealing that low-power radio AGNs are more common in denser regions.

Contribution

It provides new evidence linking environmental richness to the likelihood of hosting low-power radio AGNs up to high redshift.

Findings

Radio AGNs are in richer environments than non-radio galaxies.

The environmental effect is significant mainly for low-power radio sources.

Denser environments increase the probability of hosting radio AGNs.

Abstract

This work studies the correlation among environmental density and radio AGN presence up to $z = 2$. Using data from the photometric COSMOS survey and its radio 1.4 GHz follow-up (VLA-COSMOS), a sample of radio AGNs has been defined. The environment was studied using the richness distributions inside a parallelepiped with base side of 1 Mpc and height proportional to the photometric redshift precision. Radio AGNs are found to be always located in environments significantly richer than those around galaxies with no radio emission. Moreover, a distinction based on radio AGN power shows that the significance of the environmental effect is only maintained for low-power radio sources. The results of this work show that denser environments play a significant role in enhancing the probability that a galaxy hosts a radio AGN and, in particular, low-power ones.