The environmental properties of radio-emitting AGN. Issue 3 (17th May 2018)

• Record Type: Journal Article
• Authors: Magliocchetti, M; Popesso, P; Brusa, M; Salvato, M
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 478:Issue 3(2018)
• Page Start: 3848
• Page End: 3854
• Publication Date: 2018-05-17
• Subjects: galaxies: active -- galaxies: starburst -- dark matter -- large-scale structure of Universe -- cosmology: observations -- radio continuum: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty1309
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We study the environmental properties of z ≲ 1.2 radio-selected active galactic nuclei (AGNs) belonging to the ∼2 deg 2 of the COSMOS field, finding that about 20 per cent of them appear within overdense structures. AGNs with $P_{1.4 \ \rm GHz}\gt 10^{23.5} \ \rm W\ Hz^{-1}\ sr^{-1}$ are twice more likely to be found in clusters with respect to fainter sources (∼38 per cent vs ∼15 per cent), just as radio-selected AGNs with stellar masses M * > 10 11 M⊙ are twice more likely to be found in overdense environments with respect to objects of lower mass (∼24 per cent vs ∼11 per cent). Comparisons with galaxy samples further suggest that radio-selected AGN of large stellar mass tend to avoid underdense environments more than normal galaxies with the same stellar content. Stellar masses also seem to determine the location of radio-active AGN within clusters: ∼100 per cent of the sources found as satellite galaxies have M * < 10 11.3 M⊙, while ∼100 per cent of the AGNs coinciding with a cluster central galaxy have M * > 10 11 M⊙ . No different location within the cluster is instead observed for AGN of various radio luminosities. Radio AGN, which also emit in the Mid-Infrared show a marked preference to be found as isolated galaxies (∼70 per cent) at variance with those also active in the X-ray that all seem to reside within overdensities. What emerges from our work is a scenario whereby physical processes on sub-pc and kpc scales (e.g. emission, respectively, related to the AGN and to star formation) are strongly interconnected with the large-scale environment of the AGN itself.