2015AJ....149..191L

In this paper, we investigated the issue of black hole masses and minimum timescales of jet emission for blazars. We proposed a sophisticated model that sets an upper limit to the central black hole masses M_* with the minimum timescales Δt_min^ob of variations observed in blazars. The value of Δt_min^ob presents an upper limit to the size of the blob in the jet. The blob is assumed to be generated in the jet-production region in the vicinity of the black hole, and then the expanding blob travels outward along the jet. We applied the model to 32 blazars, 29 of which were detected in gamma-rays by satellites, and these Δt_min^ob are on the order of hours, with large variability amplitudes. In general, the M_* estimated with this method are not inconsistent with those masses reported in the literature. This model is natural for connecting Δt_min^ob with Δt_min^ob for blazars, and seems to be applicable in constraining Δt_min^ob in the central engines of blazars.