ABSTRACT. We consider the consequences of gravitational wave recoil for unified models of active galactic nuclei (AGNs). Spatial oscillations of supermassive black holes (SMBHs) around the cores of galaxies following gravitational wave (GW) recoil imply that the SMBHs spend a significant fraction of time off-nucleus, at scales beyond that of the molecular obscuring torus. Assuming reasonable distributions of recoil velocities, we compute the off-core timescale of (intrinsically type 2) quasars. We find that roughly one-half of major mergers result in a SMBH being displaced beyond the torus for a time of 10^7.5 yr or more, comparable to quasar activity timescales. Since major mergers are most strongly affected by GW recoil, our results imply a deficiency of type 2 quasars in comparison to Seyfert 2 galaxies. Other consequences of the recoil oscillations for the observable properties of AGNs are also discussed.

Subject headings: galaxies: active; galaxies: evolution; quasars: general

Print publication: Issue 2 (2008 December 20)
Received 2008 September 24, accepted for publication 2008 October 28
Published 2008 November 6