A LOW-MASS BLACK HOLE IN THE NEARBY SEYFERT GALAXY UGC 06728

Abstract

We present the results of a recent reverberation mapping campaign for UGC 06728, a nearby low-luminosity Seyfert 1 in a late-type galaxy. Nightly monitoring in the spring of 2015 allowed us to determine an H β time delay of days. Combined with the width of the variable H β line profile, we determine a black hole mass of . We also constrain the bulge stellar velocity dispersion from higher-resolution long-slit spectroscopy along the galaxy minor axis and find km s −1 . The measurements presented here are in good agreement with both the relationship and the relationship for active galactic nuclei. Combined with a previously published spin measurement, our mass determination for UGC 06728 makes it the lowest-mass black hole that has been fully characterized, and thus an important object to help anchor the low-mass end of black hole evolutionary models.