Kick & spin: new probes for multi-messenger black-hole mergers in AGNs

Fuente: arXiv
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Main Authors: Leong, Samson H. W., Bustillo, Juan Calderón
Format: Preprint
Published: 2025
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author Leong, Samson H. W.
Bustillo, Juan Calderón
author_facet Leong, Samson H. W.
Bustillo, Juan Calderón
contents Recoiling remnants of black-hole mergers in dense environments can produce bright electromagnetic (EM) counterparts to the gravitational-wave (GW) emission. Significance assessments of such GW-EM candidates are restricted to time and sky-localisation consistency, omitting the physics governing the EM emission process. Different emission mechanisms, however, impose different observability constraints on the remnant black-hole recoil and spin, which are gravitational-wave observables. We present a statistical framework that includes such parameters. We assess the consistency of the GW190521-ZTF19abanrhr pair with two types of emission processes: a Blandford-Znajek jet closely aligned with the final spin axis and a diffusive isotropic flare. Assuming the sky-location of ZTF19abanrhr, we find these mechanisms to be respectively strongly and moderately disfavoured with log-evidences $\log_{10}{\cal I}_{\rm jet} = -1.65$ and $\log_{10}{\cal I}_{\rm diff} = -0.075$. Combining these with odds for a common sky-location $Ω$ we obtain respective combined odds $\log_{10} {\cal O}_{Ω,{\rm jet}}= -1.17$ and $\log_{10} {\cal O}_{Ω,{\rm diff}}= +0.39$ for a true GW-EM coincidence as opposed to a random one. Our method leverages a previously unexplored evidence axis to assess GW-EM associations and constrain both the physics powering flare mechanisms and the properties of AGNs.
format Preprint
id arxiv_https___arxiv_org_abs_2512_08382
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Kick & spin: new probes for multi-messenger black-hole mergers in AGNs
Leong, Samson H. W.
Bustillo, Juan Calderón
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Recoiling remnants of black-hole mergers in dense environments can produce bright electromagnetic (EM) counterparts to the gravitational-wave (GW) emission. Significance assessments of such GW-EM candidates are restricted to time and sky-localisation consistency, omitting the physics governing the EM emission process. Different emission mechanisms, however, impose different observability constraints on the remnant black-hole recoil and spin, which are gravitational-wave observables. We present a statistical framework that includes such parameters. We assess the consistency of the GW190521-ZTF19abanrhr pair with two types of emission processes: a Blandford-Znajek jet closely aligned with the final spin axis and a diffusive isotropic flare. Assuming the sky-location of ZTF19abanrhr, we find these mechanisms to be respectively strongly and moderately disfavoured with log-evidences $\log_{10}{\cal I}_{\rm jet} = -1.65$ and $\log_{10}{\cal I}_{\rm diff} = -0.075$. Combining these with odds for a common sky-location $Ω$ we obtain respective combined odds $\log_{10} {\cal O}_{Ω,{\rm jet}}= -1.17$ and $\log_{10} {\cal O}_{Ω,{\rm diff}}= +0.39$ for a true GW-EM coincidence as opposed to a random one. Our method leverages a previously unexplored evidence axis to assess GW-EM associations and constrain both the physics powering flare mechanisms and the properties of AGNs.
title Kick & spin: new probes for multi-messenger black-hole mergers in AGNs
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2512.08382