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arXiv · 1708.02251

The Properties of Radio Galaxies and the Effect of Environment in Large Scale Structures at $z\sim1$

Lu Shen·Neal A. Miller·Brian C. Lemaux·Adam R. Tomczak·Lori M. Lubin·Nicholas Rumbaugh·Christopher D. Fassnacht·Robert H. Becker·Roy R. Gal·Po-Feng. Wu·Gordon Squires
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Abstract

In this study we investigate 89 radio galaxies that are spectroscopically-confirmed to be members of five large scale structures in the redshift range of $0.65 \le z \le 0.96$. Based on a two-stage classification scheme, the radio galaxies are classified into three sub-classes: active galactic nucleus (AGN), hybrid, and star-forming galaxy (SFG). We study the properties of the three radio sub-classes and their global and local environmental preferences. We find AGN hosts are the most massive population and exhibit quiescence in their star-formation activity. The SFG population has a comparable stellar mass to those hosting a radio AGN but are unequivocally powered by star formation. Hybrids, though selected as an intermediate population in our classification scheme, were found in almost all analyses to be a unique type of radio galaxies rather than a mixture of AGN and SFGs. They are dominated by a high-excitation radio galaxy (HERG) population. We discuss environmental effects and scenarios for each sub-class. AGN tend to be preferentially located in locally dense environments and in the cores of clusters/groups, with these preferences persisting when comparing to galaxies of similar colour and stellar mass, suggesting that their activity may be ignited in the cluster/group virialized core regions. Conversely, SFGs exhibit a strong preference for intermediate-density global environments, suggesting that dusty starbursting activity in LSSs is largely driven by galaxy-galaxy interactions and merging.

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Lu Shen, Neal A. Miller, Brian C. Lemaux, Adam R. Tomczak, Lori M. Lubin, Nicholas Rumbaugh, Christopher D. Fassnacht, Robert H. Becker, Roy R. Gal, Po-Feng. Wu, Gordon Squires. 2017-08-07. The Properties of Radio Galaxies and the Effect of Environment in Large Scale Structures at $z\sim1$. https://doi.org/10.1093/mnras%2Fstx1984

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