Unifying spatial correlation with hierarchical population inference to constrain the AGN channel for binary black hole mergers

arXiv (Cornell University)

Abstract

The origin of the stellar-mass binary black holes (BBHs) observed in gravitational wave (GW) events by the LIGO-Virgo-KAGRA (LVK) detectors remains uncertain. One promising formation pathway is the active galactic nucleus (AGN) channel, in which BBHs embedded in AGN accretion discs experience enhanced merger rates and may produce rapidly spinning black holes in the upper mass gap. Previous constraints on the AGN contribution to the LVK merger population have relied either on spatial correlations between GW localisations and AGN catalogues or on modelling the intrinsic properties of GW sources. We develop a hierarchical Bayesian framework that unifies these approaches within a single likelihood for the fraction of AGN-hosted GW events, $f_{\rm agn}$. This framework, combined with the latest gravitational wave transient catalogue GWTC-5.0 and the electromagnetic Quaia AGN catalogue, cannot exclude an AGN contribution to the observed merger rate. For unobscured AGN in the optical and infrared bands with bolometric luminosities $L_{\rm bol}\geq\{10^{44.5},10^{45.5},10^{46.5}\}\,\mathrm{erg\,s^{-1}}$, we exclude $f_{\rm agn} \geq \{0.52,0.41, 0.61\}$ at the 95 percent credible level under our fiducial model. The methodology and results presented in this work lay down the pathway for combining the full GW posterior with electromagnetic observations to infer the properties of GW populations and AGN discs.

Authors 4

1. Lucas Pouw Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

2. Lorenzo Speri Aachen Leiden Observatory

   Leiden University · European Space Agency · Leiden Observatory · European Space Research and Technology Centre

   Affiliation as printed

   European Space Agency (ESA) , European Space Research and Technology Centre (ESTEC) , Keplerlaan 1 , 2201 AZ Noordwijk , the Netherlands

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands

3. Niccolò Veronesi

   Washington State University

   Affiliation as printed

   Department of Physics and Astronomy , Washington State University , Pullman , WA 99164 , USA

4. Elena Maria Rossi Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands