Fermi Gamma-ray Space Telescope

Correlations among Jet, Accretion Disk, and Broad Line Region of Flat Spectrum Radio Quasars

J. Zhang
Z. W. Xue, J. J. He, E. W. Liang, S. N. Zhang

Abstract:

On the basis of the spectral energy distribution fits and emission line fluxes of 18 GeV flat spectrum radio quasars (FSRQs), we calculate their jet power (P_jet), disk luminosity (L_disk), and broad-line region (BLR) luminosity (L_BLR). No correlation between P_jet with either L_disk or L_BLR is found, but L_BLR is strongly correlated with L_disk. On average, the BLR covering factors of GeV-FSRQs in our sample are smaller than those of large samples of quasars. P_jet of some GeV-FSRQs are higher than their L_disk, but all of them are lower than the accretion power of black holes (BHs), which is estimated by M^dot*c^2=L_disk/0.1, indicating that the total accretion power of BHs is sufficient to drive the jets in these sources; however, lack of correlation between L_disk and P_jet of the GeV-FSRQs may suggest that their jets are launched by the Blandford?Znajek process via extracting the rotational energy of BHs. Using the L_BLR?L_disk relation of the GeV-FSRQs, we estimate L_disk of a BL Lac sample with their L_BLR. A comparison of L_BLR and the Eddington ratio (L_disk/L_Edd) among BL Lacs, very radio-loud NLS1 galaxies, and FSRQs is also presented. It is found that along with the BL Lac?NLS1?FSRQ sequence L_BLR and L_disk/L_Edd increase, which may correspond to the change of the accretion disk structure and the transformation of the dominant mechanism for jet launching. This is also consistent with the division of blazar parent populations, i.e., low/high-excitation radio galaxies.