MBH–σ relation in Sloan Digital Sky Survey flat-spectrum radio quasars

The relationship between the black hole mass and velocity dispersion indicated with [O iii] linewidth is investigated for a sample of 87 flat-spectrum radio quasars selected from the Sloan Digital Sky Survey Data Release 3 quasar catalogue. We found that the M-BH-Sigma([O III]) relation is different from the Tremaine et al. relation for nearby inactive galaxies, with a larger black hole mass at given velocity dispersion. There is no strong evidence of cosmology evolution in the M-BH-Sigma([O III]) relation up to z similar to 0.8. A significant correlation between the [O iii] luminosity and broad-line region (BLR) luminosity is found. When transferring the [O iii] luminosity to narrow-line region (NLR) luminosity, the BLR luminosity is, on average, larger than the NLR one by about one order of magnitude. We found a strong correlation between the synchrotron peak luminosity and NLR luminosity, which implies a tight relation between the jet physics and accretion process.