# Constraining Recoiling Velocities of Black Holes Ejected by Gravitational Radiation in Galaxy Mergers

## TL;DR

This paper explores how polarization data of accretion disks can be used to estimate the recoil velocities of black holes ejected during galaxy mergers, linking gravitational wave physics with observable AGN features.

## Contribution

It introduces a method to constrain black hole recoil velocities using polarization measurements of accretion disk emission.

## Key findings

- Polarization data can determine black hole recoil velocities.
- Recoil velocities can reach thousands of km/s.
- Method links gravitational wave recoil with observable AGN properties.

## Abstract

Recent general relativistic simulations have shown that the coalescence of two spinning black holes (BH) can lead to recoiling speeds of the BH remnant of up to thousands of km/s as a result of the gravitational radiation emission. It is important that the accretion disc remains bound to ejected BH within the region where the gas orbital velocity is larger than the ejection speed. We considered the situation when the recoiling kick radius coincides with the radius of the broad line region (BLR). We show that in this situation the observed polarization data of accretion disk emission allow to determine the value of the recoil velocity. We present the estimates of the kick velocity for AGN with determined polarization data.