1. 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
- Author
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Hisakazu Uchiyama, Takuji Yamashita, Tohru Nagao, Kohei Ichikawa, Yoshiki Toba, Shogo Ishikawa, Mariko Kubo, Masaru Kajisawa, Toshihiro Kawaguchi, Nozomu Kawakatu, Chien-Hsiu Lee, and Akatoki Noboriguchi
- Subjects
Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics::Galaxy Astrophysics - Abstract
We examine the redshift evolution of density environments around 2,163 radio galaxies with the stellar masses of $\sim10^{9}-10^{12} M_\odot$ between redshifts of $z=0.3-1.4$, based on the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) and Faint Images of the Radio Sky at Twenty-cm (FIRST). We use the $k$-nearest neighbor method to measure the local galaxy number density around our radio galaxy sample. We find that the overdensities of the radio galaxies are weakly but significantly anti-correlated with redshift. This is consistent with the known result that the relative abundance of less-massive radio galaxies increases with redshift, because less-massive radio galaxies reside in relatively low density regions. Massive radio galaxies with stellar mass of $M_* >10^{11}M_\odot$ are found in high density environments compared with the control sample galaxies with radio-non-detection and matched-stellar-mass. Less-massive radio galaxies with $M_* 10^{11}M_\odot$ ($M_* 1.4$, while less-massive radio galaxies undergo active accretion just at this epoch, as they have avoided such merger events., 14 pages, 8 figures, ApJ accepted
- Published
- 2022