Understanding the high-mass binary black hole population from stable mass transfer and super-Eddington accretion in <scp>bpass</scp>

Briel, M. M.; Stevance, H. F.; Eldridge, J. J.

doi:10.1093/mnras/stad399

“…In particular, van Son et al (2022b) found that more massive BHs are formed exclusively by the stable mass transfer channel, while the common envelope channel dominates the formation of lower-mass systems. This result was confirmed by Belczynski et al (2022) and Briel et al (2023). Given the distinct delay time distributions of these two channels (Figure 1), this implies a mass dependence of the delay time distribution.…”

Section: Discussion On Simplifying Assumptionssupporting

confidence: 62%

LIGO–Virgo–KAGRA's Oldest Black Holes: Probing Star Formation at Cosmic Noon With GWTC-3

Fishbach,

van Son

2023

ApJL

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In their third observing run, the LIGO–Virgo–KAGRA gravitational-wave (GW) observatory was sensitive to binary black hole (BBH) mergers out to redshifts z merge ≈ 1. Because GWs are inefficient at shrinking the binary orbit, some of these BBH systems likely experienced long delay times τ between the formation of their progenitor stars at z form and their GW merger at z merge. In fact, the distribution of delay times predicted by isolated binary evolution resembles a power law p ( τ ) ∝ τ α τ with slope −1 ≲ α τ ≲ −0.35 and a minimum delay time of τ min = 10 Myr . We use these predicted delay time distributions to infer the formation redshifts of the ∼70 BBH events reported in the third GW transient catalog GWTC-3 and the formation rate of BBH progenitors. For our default α τ = –1 delay time distribution, we find that GWTC-3 contains at least one system (with 90% credibility) that formed earlier than z form > 4.4. Comparing our inferred BBH progenitor formation rate to the star formation rate, we find that at z form = 4, the number of BBH progenitor systems formed per stellar mass was 6.4 − 5.5 + 9.4 × 10 − 6 M ⊙ − 1 and this yield dropped to 0.134 − 0.127 + 1.6 × 10 − 6 M ⊙ − 1 by z form = 0. We discuss implications of this measurement for the cosmic metallicity evolution, finding that for typical assumptions about the metallicity dependence of the BBH yield, the average metallicity at z form = 4 was 〈 log 10 ( Z / Z ⊙ ) 〉 = − 0.3 − 0.4 + 0.3 , although the inferred metallicity can vary by a factor of ≈3 for different assumptions about the BBH yield. Our results highlight the promise of current GW observatories to probe high-redshift star formation.

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“…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%

The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers

Oh

¹

,

Fishbach

²

,

Kimball

³

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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“…Radiation, generalrelativistic, and magneto-hydrodynamics simulation of a supercritical accretion disk around BHs (e.g., S ądowski & Narayan 2016) suggest that the accretion rate may significantly exceed the Eddington limit. This possibility has been explored in the context of BH high-mass X-ray binaries (Moreno Méndez et al 2008;Qin et al 2022) and coalescing binary BH populations (e.g., Bavera et al 2021;Briel et al 2023). However, the effect of super-Eddington accretion on the formation and the properties of merging NSBH, and especially the probability of being accompanied by EMCs, is less well studied.…”

Section: Uncertainties In Stellar and Binary Physicsmentioning

confidence: 99%

From ZAMS to merger: Detailed binary evolution models of coalescing neutron star – black hole systems at solar metallicity

Xing,

Bavera,

Fragos

et al. 2024

A&A

2

0

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Neutron star -- black hole (NSBH) merger events bring us new opportunities to constrain theories of stellar and binary evolution and understand the nature of compact objects. In this work, we investigated the formation of merging NSBH binaries at solar metallicity by performing a binary population synthesis study of merging NSBH binaries with the newly developed code POSYDON sun sun $. Independently of our model variations, the BH always forms first with dimensionless spin parameter $ 0.2$, which is correlated to the initial binary orbital period. Some BHs can subsequently spin up moderately ($ BH 0.4$) due to mass transfer, which we assume to be Eddington limited. Binaries that experience CE evolution rarely demonstrate large tilt angles. Conversely, approximately $40<!PCT!>$ of the binaries that undergo only stable mass transfer without CE evolution contain an anti-aligned BH. Finally, accounting for uncertainties in both the population modeling and the NS equation of state, we find that $0-18.6<!PCT!>$ of NSBH mergers may be accompanied by an electromagnetic counterpart.

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Understanding the high-mass binary black hole population from stable mass transfer and super-Eddington accretion in bpass

Cited by 31 publications

References 148 publications

LIGO–Virgo–KAGRA's Oldest Black Holes: Probing Star Formation at Cosmic Noon With GWTC-3

LIGO–Virgo–KAGRA's Oldest Black Holes: Probing Star Formation at Cosmic Noon With GWTC-3

The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers

From ZAMS to merger: Detailed binary evolution models of coalescing neutron star – black hole systems at solar metallicity

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