Suspicious Siblings: The Distribution of Mass and Spin across Component Black Holes in Isolated Binary Evolution

Zevin, M.; Bavera, Simone S.

doi:10.3847/1538-4357/ac6f5d

Cited by 41 publications

(10 citation statements)

References 111 publications

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“…(Because the mass ratio is calculated as the mass of the initially less massive secondary divided by the mass of the initially more massive primary, CE+MRR compact object binaries have mass ratios greater than 1.) Our findings agree with Zevin & Bavera (2022) who find that MRR rarely leads to mass ratios smaller than 1/3.…”

Section: Forming Asymmetric Systemssupporting

confidence: 93%

“…There are additional uncertainties in binary population synthesis that we did not explore in this work. For example, it has been proposed that super-Eddington accretion onto the first-born BH can dramatically increase its mass and lead to more asymmetric systems (Bavera et al 2021;Briel et al 2022;Zevin & Bavera 2022). However, such conservative mass transfer is not as efficient as nonconservative mass transfer in shrinking the orbit, and so this scenario may not contribute much to the merger rate.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have explored pathways within isolated binary evolution that lead to asymmetric BBH or NSBH mergers, usually focusing on one type of binary, either BBH or NSBH, and often within the context of the NS/BH mass gap (e.g., Olejak et al 2020;Zevin et al 2020;Broekgaarden et al 2021;Antoniadis et al 2022;Zevin & Bavera 2022). In this work, we consider both BBH and NSBH asymmetric systems, and investigate the evolutionary pathways that lead them to form and merge within the context of isolated binary evolution.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers

Fishbach

Kimball

et al. 2023

ApJ

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In their most recent observing run, the LIGO-Virgo-KAGRA Collaboration observed gravitational waves from compact binary mergers with highly asymmetric mass ratios, including both binary black holes (BBHs) and neutron star-black holes (NSBHs). It appears that NSBHs with mass ratios q ≃ 0.2 are more common than equally asymmetric BBHs, but the reason for this remains unclear. We use the binary population synthesis code cosmic to investigate the evolutionary pathways leading to the formation and merger of asymmetric compact binaries. We find that within the context of isolated binary stellar evolution, most asymmetric mergers start off as asymmetric stellar binaries. Because of the initial asymmetry, these systems tend to first undergo a dynamically unstable mass transfer phase. However, after the first star collapses into a compact object, the mass ratio is close to unity and the second phase of mass transfer is usually stable. According to our simulations, this stable mass transfer fails to shrink the orbit enough on its own for the system to merge. Instead, the natal kick received by the second-born compact object during its collapse is key in determining how many of these systems can merge. For the most asymmetric systems with mass ratios of q ≤ 0.1, the merging systems in our models receive an average kick magnitude of 255 km s−1 during the second collapse, while the average kick for non-merging systems is 59 km s−1. Because lower mass compact objects, like neutron stars, are expected to receive larger natal kicks than higher mass BHs, this may explain why asymmetric NSBH systems merge more frequently than asymmetric BBH systems.

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Section: Forming Asymmetric Systemssupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers

Fishbach

Kimball

et al. 2023

ApJ

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“…In short, binary stellar evolution consists of several processes that can break the symmetry between the population of initially more massive stars, which generally correspond to the firstborn and more massive (primary) BHs, and the population of initially less massive stars, which generally correspond to the secondborn and less massive (secondary) BHs. However, if mass inversion occurs in some systems, some initially less massive stars will end up as the more massive BHs by the time of merger, and the distribution of primary BH masses will have contributions from both the secondborn and firstborn BHs (Olejak & Belczynski 2021;Broekgaarden et al 2022;Hu et al 2022;Zevin & Bavera 2022). If mass inversion happens in exactly half of merging BBH systems, the primary and secondary component mass distributions may be indistinguishable even if the firstand secondborn distributions differ.…”

Section: Introductionmentioning

confidence: 99%

Two of a Kind: Comparing Big and Small Black Holes in Binaries with Gravitational Waves

Farah,

Fishbach,

Holz

2024

ApJ

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When modeling the population of merging binary black holes, analyses have generally focused on characterizing the distribution of primary (i.e., more massive) black holes in the binary, while using simplistic prescriptions for the distribution of secondary masses. However, the secondary mass distribution and its relationship to the primary mass distribution provide a fundamental observational constraint on the formation history of coalescing binary black holes. If both black holes experience similar stellar evolutionary processes prior to collapse, as might be expected in dynamical formation channels, the primary and secondary mass distributions would show similar features. If they follow distinct evolutionary pathways (for example, due to binary interactions that break symmetry between the initially more massive and less massive stars), their mass distributions may differ. We present the first analysis of the binary black hole population that explicitly fits for the secondary mass distribution. We find that the data is consistent with a ∼30 M ⊙ peak existing only in the distribution of secondary rather than primary masses. This would have major implications for our understanding of the formation of these binaries. Alternatively, the data is consistent with the peak existing in both component mass distributions, a possibility not included in most previous studies. In either case, the peak is observed at 31.4 − 2.6 + 2.3 M ⊙ , which is shifted lower than the value obtained in previous analyses of the marginal primary mass distribution, placing this feature in further tension with expectations from a pulsational pair-instability supernova pileup.

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“…Typically, the firstborn black hole forms the primary (more massive) black hole. However, if the binary undergoes mass-ratio reversal, the second-born (i.e., spinning) black hole will be the more massive component (Broekgaarden et al 2022;Zevin & Bavera 2022). If the black holes seen with gravitational waves form in the field and are tidally spun up, we expect that only one black hole in any given binary should have nonnegligible spin.…”

Section: Introductionmentioning

confidence: 99%

Which Black Hole Is Spinning? Probing the Origin of Black Hole Spin with Gravitational Waves

Adamcewicz,

Galaudage,

Lasky

et al. 2024

ApJL

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Theoretical studies of angular momentum transport suggest that isolated stellar-mass black holes are born with negligible dimensionless spin magnitudes χ ≲ 0.01. However, recent gravitational-wave observations indicate ≳40% of binary black hole systems contain at least one black hole with a nonnegligible spin magnitude. One explanation is that the firstborn black hole spins up the stellar core of what will become the second-born black hole through tidal interactions. Typically, the second-born black hole is the “secondary” (less massive) black hole though it may become the “primary” (more massive) black hole through a process known as mass-ratio reversal. We investigate this hypothesis by analyzing data from the third gravitational-wave transient catalog using a “single-spin” framework in which only one black hole may spin in any given binary. Given this assumption, we show that at least 28% (90% credibility) of the LIGO–Virgo–KAGRA binaries contain a primary with significant spin, possibly indicative of mass-ratio reversal. We find no evidence for binaries that contain a secondary with significant spin. However, the single-spin framework is moderately disfavored (natural log Bayes factor ln B = 3.1 ) when compared to a model that allows both black holes to spin. If future studies can firmly establish that most merging binaries contain two spinning black holes, it may call into question our understanding of formation mechanisms for binary black holes or the efficiency of angular momentum transport in black hole progenitors.

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Suspicious Siblings: The Distribution of Mass and Spin across Component Black Holes in Isolated Binary Evolution

Cited by 41 publications

References 111 publications

The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers

The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers

Two of a Kind: Comparing Big and Small Black Holes in Binaries with Gravitational Waves

Which Black Hole Is Spinning? Probing the Origin of Black Hole Spin with Gravitational Waves

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