Do radio-loud AGN really follow the same relation between black hole mass and stellar velocity dispersion as normal galaxies?

TL;DR

This study investigates whether radio-loud AGNs follow the same black hole mass and stellar velocity dispersion relation as normal galaxies, accounting for observational effects, and finds persistent deviations suggesting intrinsic differences or measurement issues.

Contribution

The paper corrects for relativistic beaming and orientation effects in radio-loud AGNs and compares their black hole mass-velocity dispersion relation to that of normal galaxies, revealing persistent deviations.

Findings

Radio-loud AGNs deviate from the established black hole mass-velocity dispersion relation.

No significant correlation between radio jet power and narrow [OIII] line width.

Deviations may be intrinsic or due to [OIII] line width not being a reliable indicator.

Abstract

In an examination of the relationship between the black hole mass and stellar velocity dispersion 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 relation between black hole mass and stellar velocity dispersion which derived from [OIII] line width 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 relation between black hole mass and stellar velocity dispersion of radio-loud AGNs is intrinsic, or that the [OIII] line width is not a good indicator of stellar velocity dispersion for radio-loud AGNs.