2003AJ....126.2108X

We have compiled sample of 17 GeV γ-ray-loud blazars, for which rapid optical variability and γ-ray fluxes are well observed, from the literature. We derive estimates of the masses, the minimum Kerr parameters a_min, and the size of the emission regions of the supermassive black holes (SMBHs) for the blazars in the sample from their minimum optical variability timescales and γ-ray fluxes. The results show that (1) the masses derived from the optical variability timescale (M_H) are significantly correlated with the masses from the γ-ray luminosity (M^KN_H); (2) the values of a_minof the SMBHs with masses M_H≥10^8.3 M_☉(three out of 17 objects) range from ∼0.5 to ∼1.0, suggesting that these SMBHs are likely to be Kerr black holes. For the SMBHs with M_H_<10^8.3 M_☉, however, a_min=0, suggesting that a nonrotating black hole model cannot be ruled out for these objects. In addition, the values of the size of the emission region, r*, for the two kinds of SMBHs are significantly different. For the SMBHs with a_min>0, the sizes of the emission regions are almost within the horizon (2r_G_) and marginally bound orbit (4r_G), while for those with a_min=0 they are in the range (4.3-66.4)r_G, extending beyond the marginally stable orbit (6r_G). These results may imply that (1) the rotational state, the radiating regions, and the physical processes in the inner regions for the two kinds of SMBH are significantly different and (2) the emission mechanisms of GeV γ-ray blazars are related to the SMBHs in their centers but are not related to the two different kinds of SMBH.