THE ENVIRONMENTAL DEPENDENCE OF THE AGE OF ACTIVE GALAXIES AND THE DEPENDENCE OF THE CLUSTERING PROPERTIES OF ACTIVE GALAXIES ON AGE

Abstract

We explore the environmental dependence of the age and the clustering-age dependence of active galaxies in two volume-limited active galaxy samples of the SDSS. In the luminous volume-limited sample, the age of active galaxies apparently depends on environments: at low density the fraction of young galaxies with ages less than 2 Gyr is significantly higher than the one in the high density case, at high density the fraction of old galaxies is significantly higher than the one at low density. Young active galaxies have a higher prevalence than old ones at small mul-tiplicity, corresponding to isolated galaxies, close pairs and small groups, whereas-old active galaxies have a higher prevalence in the multiplicity bins corresponding to dense groups and clusters. But in the faint volume-limited sample, although the environmental dependence of the age is fairly weak, a substantial clustering-age dependence can be observed.