The black hole mass of BL Lacs from stellar velocity dispersion of the host galaxy

Abstract

We present the first results from our on-going program to estimate black hole masses [M(BH)] of nearby BL Lac objects. The estimates are based on stellar velocity dispersion (sigma) of the BL Lac host galaxies from optical spectroscopy, and the recently found tight correlation between M{BH} and sigma in nearby early-type galaxies. For the first three BL Lacs, we find log M(BH) = 7.5 - 8.7 and M(BH)/M(host) = 0.03 - 0.1.Comment: 2 pages, to appear in ESO Astrophysics Symposium "The Mass of Galaxies at Low and High Redshift", eds. R. Bender & A. Renzin