Runaway Coalescence of Pre-common-envelope Stellar Binaries

MacLeod, Morgan; Loeb, Abraham

doi:10.3847/1538-4357/ab822e

Cited by 30 publications

(16 citation statements)

References 44 publications

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“…Third, E bind values computed from single stellar models represent the binding energy at the point of RLOF rather than at the onset of the CE phase. In reality, before the mass transfer rate increases sufficiently and the system becomes dynamically unstable, a giant donor is likely going to lose a sizable part of its envelope as a result of pre-CE mass transfer (MacLeod & Loeb 2020b). This could mean that E bind values relevant for the CE evolution are smaller than those calculated in Sect.…”

Section: How Robust Is the Prediction That Ce Evolution In Bhmentioning

confidence: 87%

It has to be cool: Supergiant progenitors of binary black hole mergers from common-envelope evolution

Klencki

Nelemans

Istrate

et al. 2021

A&A

135

122

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Common-envelope (CE) evolution in massive binary systems is thought to be one of the most promising channels for the formation of compact binary mergers. In the case of merging binary black holes (BBHs), the essential CE phase takes place at a stage when the first BH is already formed and the companion star expands as a supergiant. We aim to decipher the kinds of BH binaries with supergiant companions that could potentially evolve through and survive a CE phase. To this end, we compute envelope binding energies from detailed massive stellar models at different evolutionary stages and metallicities. We make multiple physically extreme choices of assumptions that favor easier CE ejection as well as account for recent advancements in mass-transfer stability criteria. We find that even with the most optimistic assumptions, a successful CE ejection in BH binaries is only possible if the donor is a massive convective-envelope giant, namely a red supergiant (RSG). The same is true for neutron-star binaries with massive companions. In other words, pre-CE progenitors of BBH mergers are BH binaries with RSG companions. We find that because of its influence on the radial expansion of massive giants, metallicity has an indirect but a very strong effect on the chemical profile, density structure, and the binding energies of RSG envelopes. Our results suggest that merger rates from population-synthesis models could be severely overestimated, especially at low metallicity. Additionally, the lack of observed RSGs with luminosities above log(L/L⊙) ≈ 5.6 − 5.8, corresponding to stars with M ≳ 40 M⊙, puts into question the viability of the CE channel for the formation of the most massive BBH mergers. Either such RSGs elude detection due to very short lifetimes, or they do not exist and the CE channel can only produce BBH systems with total mass ≲50 M⊙. Finally, we discuss an alternative CE scenario in which a partial envelope ejection is followed by a phase of possibly long and stable mass transfer.

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Section: How Robust Is the Prediction That Ce Evolution In Bhmentioning

confidence: 87%

It has to be cool: Supergiant progenitors of binary black hole mergers from common-envelope evolution

Klencki

Nelemans

Istrate

et al. 2021

A&A

135

122

View full text Add to dashboard Cite

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“…A lot of effort has been put on this in the last few years, but the problem remains largely unconquered. Several recent studies investigate the onset of CE, when an unstable mass transfer prevents the envelope from co-rotating with the core and leads to the plunge-in of the companion inside the envelope [210,211,208,209,358].…”

Section: Common Envelope (Ce)mentioning

confidence: 99%

Formation channels of single and binary stellar-mass black holes

Mapelli

2021

Preprint

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These are exciting times for binary black hole (BBH) research. LIGO and Virgo detections are progressively drawing a spectacular fresco of BBH masses, spins and merger rates. In this review, we discuss the main formation channels of BBHs from stellar evolution and dynamics. Uncertainties on massive star evolution (e.g., stellar winds, rotation, overshooting and nuclear reaction rates), core-collapse supernovae and pair instability still hamper our comprehension of the mass spectrum and spin distribution of black holes (BHs), but substantial progress has been done in the field over the last few years. On top of this, the efficiency of mass transfer in a binary system and the physics of common envelope substantially affect the final BBH demography. Dynamical processes in dense stellar systems can trigger the formation of BHs in the mass gap and intermediate-mass BHs via hierarchical BH mergers and via multiple stellar collisions. Finally, we discuss the importance of reconstructing the cosmic evolution of BBHs.

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“…The amount of angular-momentum loss through the L2 Lagrangian point adopted in the Pavlovskii3 model, [5.76, 5.82], 3 is considered to be an upper limit whereas the standard StarTrack j loss = 1.0 used in models Pavlovskii1 and Pavlovskii2 is instead close to the lower limit as indicated by MacLeod et al (2018) and MacLeod & Loeb (2020). The maximal possible j loss which allows to avoid a stellar merger during the first TTMT and would lead to the formation of a wide BH-BH binary from Mk 34 is j loss ∈ [3.74, 3.92] (65% of j L2 of MacLeod & Loeb (2020)).…”

Section: Pavlovskii Modelsmentioning

confidence: 99%

The Uncertain Future of Massive Binaries Obscures the Origin of LIGO/Virgo Sources

Belczynski,

Romagnolo,

Olejak

et al. 2021

Preprint

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The LIGO/Virgo gravitational-wave observatories have detected at least 50 double black hole (BH) coalescences. This sample is large enough to have allowed several recent studies to draw conclusions about the implied branching ratios between isolated binaries versus dense stellar clusters as the origin of double BHs. It has also led to the exciting suggestion that the population is highly likely to contain primordial black holes. Here we demonstrate that such conclusions cannot yet be robust, because of the large current uncertainties in several key aspects of binary stellar evolution. These include the development and survival of a common envelope, the mass and angular momentum loss during binary interactions, mixing in stellar interiors, pair-instability mass loss and supernova outbursts. Using standard tools such as the rapid population synthesis codes StarTrack and COMPAS and the detailed stellar evolution code MESA, we examine as a case study the possible future evolution of Melnick 34, the most massive known binary star system (with initial component masses of 144 M and 131 M ). We show that, despite its fairly well-known orbital architecture, various assumptions regarding stellar and binary physics predict a wide variety of outcomes: from a close BH-BH binary (which would lead to a potentially detectable coalescence), through a wide BH-BH binary (which might be seen in microlensing observations), or a Thorne-Żytkow object, to a complete disruption of both objects by pair-instability supernovae. Thus since the future of massive binaries is inherently uncertain, sound predictions about the properties of BH-BH systems are highly challenging at this time. Consequently, drawing conclusions about the formation channels for the LIGO/Virgo BH-BH merger population is premature.

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Runaway Coalescence of Pre-common-envelope Stellar Binaries

Cited by 30 publications

References 44 publications

It has to be cool: Supergiant progenitors of binary black hole mergers from common-envelope evolution

It has to be cool: Supergiant progenitors of binary black hole mergers from common-envelope evolution

Formation channels of single and binary stellar-mass black holes

The Uncertain Future of Massive Binaries Obscures the Origin of LIGO/Virgo Sources

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