# Localization of Binary Black-Hole Mergers with Known Inclination

## TL;DR

This paper demonstrates that incorporating prior inclination information significantly improves the localization accuracy of binary black hole mergers detected via gravitational waves, aiding follow-up observations and astrophysical studies.

## Contribution

It provides the first realistic localizations of binary black hole mergers with prior inclination constraints, showing a threefold reduction in localization volume.

## Key findings

- Inclination priors reduce localization volume by a factor of 3.
- Improved localization enhances follow-up of electromagnetic/neutrino counterparts.
- Supports studies of mergers in active galactic nuclei disks.

## Abstract

The localization of stellar-mass binary black hole mergers using gravitational waves is critical in understanding the properties of the binaries' host galaxies, observing possible electromagnetic emission from the mergers, or using them as a cosmological distance ladder. The precision of this localization can be substantially increased with prior astrophysical information about the binary system. In particular, constraining the inclination of the binary can reduce the distance uncertainty of the source. Here we present the first realistic set of localizations for binary black hole mergers, including different prior constraints on the binaries' inclinations. We find that prior information on the inclination can reduce the localization volume by a factor of 3. We discuss two astrophysical scenarios of interest: (i) follow-up searches for beamed electromagnetic/neutrino counterparts and (ii) mergers in the accretion disks of active galactic nuclei.