SIMBAD references

Using the empirical relation between black hole mass and bulge velocity dispersion established for active and quiescent galaxies, we derive the sizes of the broad-line regions (BLRs) for 22 dwarf active galaxies. These sizes are compared with those of Seyfert 1 galaxies and quasars. We find that the size of the BLRs of Seyfert 1s and quasars is well scaled with the luminosity of the Hα line with a slope of ≃0.5, and dwarf active galaxies show larger BLRs than the values predicted by the BLR size-luminosity relation for Seyfert 1 galaxies and quasi-stellar objects (QSOs). The results suggest that the BLRs of dwarf active galactic nuclei (AGN) have lower ionization or/and lower density than those of Seyfert 1 galaxies and QSOs. Photoionization calculations show that the large BLRs are consistent with observed emission line spectra.