Mon. Not. R. Astron. Soc., 374, 691-696 (2007/January-2)
The size of broad-line regions of low-luminosity active galactic nuclei.
ZHANG X.-G., DULTZIN-HACYAN D. and WANG T.-G.
Abstract (from CDS):
We study the size of broad-line regions (BLRs) of low-luminosity active galactic nuclei (AGN), also called `dwarf AGN', defined as having LHα≤ 1041erg/s. We more than double the sample size analysed previously by Wang & Zhang. In this study we first confirm our previous result that the sizes of BLRs of low-luminosity AGN are larger than those expected from the empirical relation RBLRs-LHαvalid for `normal' AGN (Seyfert 1s and quasars), except for objects with accretion rate. Secondly, we find a positive correlation between the linewidth of the narrow emission lines (as a tracer of velocity dispersion and thus bulge and black hole mass) and the size of BLRs for both normal and low-luminosity AGN. In this paper we find a non-linear dependence of the BLR sizes of low-luminosity AGN on black hole masses. We also show that the sizes of BLRs are more strongly dominated by the `specific accretion rate', defined as, than by the masses of their central black holes. An expected result of this is that the size of the emission regions of low-ionization broad Hα of NGC 4395 should be consistent with the value from the empirical relation of RBLRs-LHα, according to the high accretion rate.