Reexamining Evidence of a Pair-Instability Mass Gap in the Binary Black Hole Population

Abstract

The fourth gravitational wave transient catalog~(GWTC-4) has enabled empirical probes of the theorized pair-instability gap in the higher end of the binary black hole~(BBH) mass-spectrum. In this letter, using flexibly parametrized models, we show that at present there is no evidence of a sharp drop-off in the spectrum of black hole masses near $40-50M_{\odot }$. We simultaneously characterize the transition in the distribution of BBH mass-ratios, effective aligned and effective precessing spins using our flexible models. From the transitions in our inferred spin and mass-ratio distributions, we find that the high-mass broad-spin sub-population has a significant fraction~($52_{-23}^{+18}\%$) of systems with mass ratios in the range $0.6-1$. This suggests that alternatives to the hypothesis of 2G+1G hierarchical systems dominating BBH formation above $\sim 40-50M_{\odot }$ are more consistent with the GWTC-4 detection sample. By comparing with the predictions of star cluster simulations, we further show that contributions from (2G+2G) systems are not abundant enough to alleviate this discrepancy. We also demonstrate the effects of strong model assumptions on this inference, which can lead to biased astrophysical interpretation from restricted priors. We note that our results do not exclude that a high-mass gap may be identified as our sample size increases. We constrain the lower bound on the location of a possible PISN cutoff still allowed within measurement uncertainties to be $(57_{-10}^{+17}{M}_{\odot })$ and discuss its implications on the S factor of ${}^{12}\mathrm{C}(\alpha ,\gamma {)}^{16}O$ at 300 kev.

Journal accepted version

References in corpus (21)

• Advanced Virgo: a 2nd generation interferometric gravitational wave detector
• Advanced LIGO
• Pulsational pair instability as an explanation for the most luminous supernovae
• The Effect of Pair-Instability Mass Loss on Black Hole Mergers
• Mind the gap: The location of the lower edge of the pair instability supernovae black hole mass gap
• Very massive stars, pair-instability supernovae and intermediate-mass black holes with the SEVN code
• One Channel to Rule Them All? Constraining the Origins of Binary Black Holes using Multiple Formation Pathways
• The 12C(a,g)16O reaction and its implications for stellar helium burning
• Hierarchical black hole mergers in young, globular and nuclear star clusters: the effect of metallicity, spin and cluster properties
• Mass-gap Mergers in Active Galactic Nuclei
• Polluting the pair-instability mass gap for binary black holes through super-Eddington accretion in isolated binaries
• Model-independent inference on compact-binary observations
• Coalescing black hole binaries from globular clusters: mass distributions and comparison to gravitational wave data from GWTC-3
• A Parameter-Free Tour of the Binary Black Hole Population
• Understanding the high-mass binary black hole population from stable mass transfer and super-Eddington accretion in BPASS
• Non-parametric inference of the population of compact binaries from gravitational wave observations using binned Gaussian processes
• Poking Holes: Looking for Gaps in LIGO/Virgo's Black Hole Population
• Hierarchical binary black hole mergers in globular clusters: mass function and evolution with redshift
• Gravitational waves carry information beyond effective spin parameters but it is hard to extract
• Exploration of features in the black hole mass spectrum inspired by non-parametric analyses of gravitational wave observations
• Where did Heavy Binaries Go? Gravitational-wave Populations Using Delaunay Triangulation with Optimized Complexity

Cited by in corpus (4)

• On the Astrophysical Origin of Binary Black Hole Subpopulations: A Tale of Three Channels?
• Evidence for Three Subpopulations of Merging Binary Black Holes at Different Primary Masses
• Measurement prospects for the pair-instability mass cutoff with gravitational waves
• Characterizing Binary Black Hole Subpopulations in GWTC-4 with Binned Gaussian Processes: On the Origins of the $35M_{\odot }$ Peak