A Parameter-Free Tour of the Binary Black Hole Population

Abstract

The continued operation of the Advanced LIGO and Advanced Virgo gravitational-wave detectors is enabling the first detailed measurements of the mass, spin, and redshift distributions of the merging binary black hole population. Our present knowledge of these distributions, however, is based largely on strongly parameteric models; such models typically assume the distributions of binary parameters to be superpositions of power laws, peaks, dips, and breaks, and then measure the parameters governing these "building block" features. Although this approach has yielded great progress in initial characterization of the compact binary population, the strong assumptions entailed leave it often unclear which physical conclusions are driven by observation and which by the specific choice of model. In this paper, we instead model the merger rate of binary black holes as an unknown \textit{autoregressive process} over the space of binary parameters, allowing us to measure the distributions of binary black hole masses, redshifts, component spins, and effective spins with near-complete agnosticism. We find the primary mass spectrum of binary black holes to be doubly-peaked, with a fairly flat continuum that steepens at high masses. We identify signs of unexpected structure in the redshift distribution of binary black holes: a uniform-in-comoving volume merger rate at low redshift followed by a rise in the merger rate beyond redshift $z\approx 0.5$. Finally, we find that the distribution of black hole spin magnitudes is unimodal and concentrated at small but non-zero values, and that spin orientations span a wide range of spin-orbit misalignment angles but are also moderately unlikely to be truly isotropic.

Minor updates to match published version. Code can be found at http://github.com/tcallister/autoregressive-bbh-inference and data can be downloaded from https://zenodo.org/doi/10.5281/zenodo.7600140

References in corpus (13)

• Array Programming with NumPy
• Advanced Virgo: a 2nd generation interferometric gravitational wave detector
• Advanced LIGO
• GW190814: Gravitational Waves from the Coalescence of a 23 M${}_{\odot }$ Black Hole with a 2.6 M${}_{\odot }$ Compact Object
• Towards models of gravitational waveforms from generic binaries II: Modelling precession effects with a single effective precession parameter
• Analysis of spin precession in binary black hole systems including quadrupole-monopole interaction
• The LIGO Open Science Center
• Where are LIGO's Big Black Holes?
• Angular Momentum Transport via Internal Gravity Waves in Evolving Stars
• Accuracy Requirements for Empirically-Measured Selection Functions
• Model-independent inference on compact-binary observations
• Do unequal-mass binary black hole systems have larger ${\chi }_{\text{eff}}$? Probing correlations with copulas in gravitational-wave astronomy
• Unmodelled Clustering Methods for Gravitational Wave Populations of Compact Binary Mergers

Cited by in corpus (38)

• The Science of the Einstein Telescope
• Resolving the Stellar-Collapse and Hierarchical-Merger origins of the Coalescing Black Holes
• GW241011 and GW241110: Exploring Binary Formation and Fundamental Physics with Asymmetric, High-Spin Black Hole Coalescence
• Gravitational wave populations and cosmology with neural posterior estimation
• PixelPop: High Resolution Nonparameteric Inference of Gravitational-Wave Populations in Multiple Dimensions
• Which black hole is spinning? Probing the origin of black-hole spin with gravitational waves
• Nonparametric analysis of correlations in the binary black hole population with LIGO-Virgo-KAGRA data
• Inferring host-galaxy properties of LIGO-Virgo-KAGRA's black holes
• Physical Models for the Astrophysical Population of Black Holes: Application to the Bump in the Mass Distribution of Gravitational Wave Sources
• Gravitational waves from mergers of Population III binary black holes: roles played by two evolution channels
• Exploring the evolution of gravitational-wave emitters with efficient emulation: Constraining the origins of binary black holes using normalising flows
• Sampling the full hierarchical population posterior distribution in gravitational-wave astronomy
• Rarity of precession and higher-order multipoles in gravitational waves from merging binary black holes
• Structure and Skewness of the Effective Inspiral Spin Distribution of Binary Black Hole Mergers
• Do both black holes spin in merging binaries? Evidence from GWTC-4 and astrophysical implications
• Reexamining Evidence of a Pair-Instability Mass Gap in the Binary Black Hole Population
• Multi-spectral Sirens: Gravitational-wave Cosmology with (Multi-) Sub-populations of Binary Black Holes
• A Mid-Thirties Crisis: Dissecting the Properties of Gravitational Wave Sources Near the 35 Solar Mass Peak
• No evidence for a dip in the binary black hole mass spectrum
• Reconstructing parametric gravitational-wave population fits from non-parametric results without refitting the data
• Probing cosmic chemical enrichment with next-generation gravitational-wave observatories
• Mass Distribution of Binary Black Hole Mergers from Young and Old Dense Star Clusters
• Seeking Spinning Subpopulations of Black Hole Binaries via Iterative Density Estimation
• Forecast Analysis of Astrophysical Stochastic Gravitational Wave Background beyond general relativity: A Case Study on Brans-Dicke Gravity
• Looking To The Horizon: Probing Evolution in the Black Hole Spectrum With Gravitational Wave Catalogs
• Probing Spin-Orbit Resonances with the Binary Black Hole Population
• Analysis and simulations of binary black hole merger spins -- the question of spin-axis tossing at black hole formation
• Evidence for Three Subpopulations of Merging Binary Black Holes at Different Primary Masses
• On the Astrophysical Origin of Binary Black Hole Subpopulations: A Tale of Three Channels?
• Mass function of stellar black holes as revealed by the LIGO-Virgo-KAGRA observations
• Comparing astrophysical models to gravitational-wave data in the observable space
• An analytical joint prior for effective spins for inference on the spin distribution of binary black holes
• Reducing systematic uncertainties in gravitational-wave population analyses by increasing the detection threshold
• Can Big Black Holes Merge with the Smallest Black Holes?
• Measurement prospects for the pair-instability mass cutoff with gravitational waves
• Where are Gaia's small black holes?
• Probing the peak of star formation with the stochastic background of binary black hole mergers
• Characterizing Binary Black Hole Subpopulations in GWTC-4 with Binned Gaussian Processes: On the Origins of the $35M_{\odot }$ Peak