Quasars with a Kick -- Black Hole Recoil in Quasars

TL;DR

This paper investigates the occurrence of high-velocity recoiling supermassive black holes in quasars, using SDSS data to identify velocity shifts and exploring potential observable flares from fallback accretion.

Contribution

It provides the first observational constraints on the frequency of high-velocity black hole recoils in quasars using broad emission line velocity shifts.

Findings

Upper limits on high-velocity recoil incidence in AGN

Potential soft X-ray flares from fallback material

Constraints on black hole merger recoil velocities

Abstract

Mergers of spinning black holes can give recoil velocities from gravitational radiation up to several thousand km/s. A recoiling supermassive black hole in an AGN can retain the inner part of its accretion disk, providing fuel for continuing AGN activity. Using AGN in the Sloan Digital Sky Survey (SDSS) that show velocity shifts of the broad emission lines relative to the narrow lines, we place upper limits on the incidence of high velocity recoils in AGN. Brief but powerful flares in soft X-rays may occur when bound material falls back into the moving accretion disk.