Open AccessThe environment of active objects in the nearby Universe
Author(s) -
Coldwell Georgina V.,
Martínez Héctor J.,
Lambas Diego G.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05713.x
Subject(s) - physics , astrophysics , quasar , radio galaxy , galaxy cluster , astronomy , galaxy group , galaxy , redshift , active galactic nucleus , universe , dark galaxy , x shaped radio galaxy , luminous infrared galaxy
We study the galaxy environment of active galaxies, radio‐loud and radio‐quiet quasars in the redshift range 0.1 ≤ z ≤ 0.25 . We use galaxies from the APM survey in order to explore the local galaxy overdensity and the b J − R colour distribution of neighbouring galaxies of these target samples. For comparison, we perform similar analysis on samples of Abell clusters with X‐ray emission, and samples of Abell clusters with richness R = 1 and 0. The projected cross‐correlations show that the samples of quasars and active galaxies reside in regions of galaxy density enhancements lower than those typical of R = 0 clusters. We also find that in the nearby Universe the local galaxy overdensities of radio‐loud and radio‐quiet quasars are comparable. The analysis of the distribution of b J − R galaxy colour indices suggests that the environment of quasars is not strongly dominated by a population of red galaxies, characteristic of rich Abell clusters, an effect that is more clearly appreciated for our sample of radio‐loud quasars.