THE GALACTIC SPIN OF AGN GALAXIES

다국어 초록 (Multilingual Abstract)

<P>Using an extensive sample of galaxies selected from the Sloan Digital Sky Survey Data Release 5, we compare the angular momentum distribution of active galactic nuclei (AGNs) with non-AGN hosting late-type galaxies. To this end we characterize galactic spin through the dimensionless angular momentum parameter lambda, which we estimate through simple dynamical considerations. Using a volume-limited sample, we find a considerable difference when comparing the empirical distributions of lambda for AGNs and non-AGN galaxies, the AGNs showing typically low lambda values and associated dispersions, while non-AGNs present higher lambda values and a broader distribution. A more striking difference is found when looking at lambda distributions in thin M-r cuts; while the spin of non-AGN galaxies presents an anticorrelation with M-r, with bright (massive) galaxies having low spins, AGN host galaxies present uniform values of lambda at all magnitudes, a behavior probably imposed by the fact that most late-type AGN galaxies present a narrow range in color, with a typical constant lambda value. We also find that the fraction of AGN hosting galaxies in our sample strongly depends on galactic spin, increasing dramatically for decreasing lambda. For AGN host galaxies, we compute the mass of their supermassive black holes and find that this value tends to be higher for low spin galaxies, even at fixed luminosity, a result that could account, to a certain extent, for the spread on the luminosity-black-hole mass relation.</P>