Seeking Spinning Subpopulations of Black Hole Binaries via Iterative Density Estimation

Fuente: arXiv
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Main Authors: Sadiq, Jam, Dent, Thomas, Lorenzo-Medina, Ana
Format: Preprint
Published: 2025
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author Sadiq, Jam
Dent, Thomas
Lorenzo-Medina, Ana
author_facet Sadiq, Jam
Dent, Thomas
Lorenzo-Medina, Ana
contents Attempts to understand the formation of binary black hole (BBH) systems detected via gravitational wave (GW) emission are affected by many unknowns and uncertainties, from both the observational and theoretical (astrophysical modelling) sides. Binary component spins have been proposed as a means to investigate formation channels, however obtaining clear inferences is challenging, given the apparently low magnitude of almost all merging BH spins and their high measurement uncertainties. Even for the effective aligned spin $χ_{\mathrm{eff}}$ which is more precisely measured than component spins, specific model assumptions have been required to identify any clear trends. Here, we reconstruct the joint component mass and $χ_{\mathrm{eff}}$ distribution of BBH mergers with minimal assumptions using the GWTC-3 catalog, using an iterative kernel density estimation (KDE)-based method. We reproduce some features seen in previous analyses, for instance a small but preferentially positive $χ_{\mathrm{eff}}$ for low-mass mergers; we also identify a possible subpopulation of higher-spin BBH with $|χ_{\mathrm{eff}}|$ up to $\sim\! 0.75$ for primary masses $m_1 \gtrsim 40\,M_\odot$, in addition to the bulk of the distribution with $|χ_{\mathrm{eff}}| \lesssim 0.2$. This finding is consistent with previous studies indicating a broader spin distribution at high mass, suggesting a distinct origin for the high-spin systems. We also identify a new potential trend of low-mass BBHs: the \emph{derivative} of $χ_{\mathrm{eff}}$ with respect to $m_1$ ($m_2$) is positive (negative) over the $10$--$15\,M_\odot$ range. This apparent structure may be related to} a previously reported anticorrelation between mass ratio and $χ_{\mathrm{eff}}$.
format Preprint
id arxiv_https___arxiv_org_abs_2506_02250
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Seeking Spinning Subpopulations of Black Hole Binaries via Iterative Density Estimation
Sadiq, Jam
Dent, Thomas
Lorenzo-Medina, Ana
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Attempts to understand the formation of binary black hole (BBH) systems detected via gravitational wave (GW) emission are affected by many unknowns and uncertainties, from both the observational and theoretical (astrophysical modelling) sides. Binary component spins have been proposed as a means to investigate formation channels, however obtaining clear inferences is challenging, given the apparently low magnitude of almost all merging BH spins and their high measurement uncertainties. Even for the effective aligned spin $χ_{\mathrm{eff}}$ which is more precisely measured than component spins, specific model assumptions have been required to identify any clear trends. Here, we reconstruct the joint component mass and $χ_{\mathrm{eff}}$ distribution of BBH mergers with minimal assumptions using the GWTC-3 catalog, using an iterative kernel density estimation (KDE)-based method. We reproduce some features seen in previous analyses, for instance a small but preferentially positive $χ_{\mathrm{eff}}$ for low-mass mergers; we also identify a possible subpopulation of higher-spin BBH with $|χ_{\mathrm{eff}}|$ up to $\sim\! 0.75$ for primary masses $m_1 \gtrsim 40\,M_\odot$, in addition to the bulk of the distribution with $|χ_{\mathrm{eff}}| \lesssim 0.2$. This finding is consistent with previous studies indicating a broader spin distribution at high mass, suggesting a distinct origin for the high-spin systems. We also identify a new potential trend of low-mass BBHs: the \emph{derivative} of $χ_{\mathrm{eff}}$ with respect to $m_1$ ($m_2$) is positive (negative) over the $10$--$15\,M_\odot$ range. This apparent structure may be related to} a previously reported anticorrelation between mass ratio and $χ_{\mathrm{eff}}$.
title Seeking Spinning Subpopulations of Black Hole Binaries via Iterative Density Estimation
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2506.02250