Do Radio-loud Active Galactic Nuclei really follow the same M BH – σ ast Relation as Normal Galaxies?

Abstract

In an examination of the relationship between the black hole mass M BH and stellar velocity dispersion σ * in radio-loud active galactic nuclei (AGNs), we studied two effects which may cause uncertainties in the black hole mass estimates of radio-loud AGNs: the relativistic beaming effect on the observed optical continuum radiation and the orientation effect on the broad emission line width. After correcting these two effects, we re-examined the M BH – σ [OIII] relation for a sample of radio-loud and radio-quiet AGNs, and found the relation for radio-loud AGNs still deviated from that for nearby normal galaxies and radio-quiet AGNs. We also found there is no significant correlation between radio jet power and narrow [OIII] line width, indicating absence of strong interaction between radio jet and narrow line region. It may be that the deviation of the M BH – σ * relation of radio-loud AGNs is intrinsic, or that the [OIII] line width is not a good indicator of σ * for radio-loud AGNs.