Mass transfer on a nuclear timescale in models of supergiant and ultra-luminous X-ray binaries

Quast, M.; Langer, N.; Tauris, T. M.

doi:10.1051/0004-6361/201935453

Cited by 41 publications

(58 citation statements)

References 93 publications

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“…If we consider a system with a 7.5 M BH at an initial orbital period of 2000 days and α CE = 1, we find that the onset of CE happens when the donor has a central helium mass fraction of Y c = 0.02, and for the entirety of its post-CE lifetime until core carbon depletion (26 000 years), it is a Rochelobe filling binary. This matches the results of Quast et al (2019) who argue that post-CE systems can undergo MT on the nuclear timescale of the donor. We expect that in cases where the star does not halt its expansion in the HG, CE evolution is initiated with a much larger value of Y c , leading to a longer lifetime as an X-ray source post-CE.…”

Section: Common Envelope In Donors With Convective Envelopessupporting

confidence: 89%

The role of mass transfer and common envelope evolution in the formation of merging binary black holes

Marchant

Pappas

Gallegos-Garcia

et al. 2021

A&A

110

117

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As the number of merging binary black holes observed with ground-based gravitational-wave detectors grows, increasingly accurate theoretical models are required to compare them to the observed sample and disentangle contributions from multiple channels. In formation models involving isolated binary stars, important uncertainties remain regarding the stability of mass transfer and common-envelope evolution. To study some of these uncertainties, we have computed binary simulations using the MESA code consisting of a 30 M⊙ star in a low metallicity (Z⊙/10) environment with a black-hole companion. We have developed an updated prescription to compute mass transfer rates including the possibility of outflows from outer Lagrangian points, as well as a method to self-consistently determine the core-envelope boundary in cases where there is common-envelope evolution. We find that binaries survive common-envelope evolution only if unstable mass transfer happens after the formation of a deep convective envelope, resulting in a narrow range (0.2 dex) in period for successful envelope ejection. All cases where binary interaction is initiated with a radiative envelope have large binding energies (∼1050 erg), and they result in mergers during the common-envelope phase even under the assumption that all the internal and recombination energy of the envelope, as well as the energy from an inspiral, is used to eject the envelope. This is independent of whether or not helium is ignited in the core of the donor, conditions under which various rapid-population synthesis calculations assume a successful envelope ejection is possible. Moreover, we find that the critical mass ratio for instability is such that across a large range in initial orbital periods (∼1−1000 days), merging binary black holes can be formed via stable mass transfer. A large fraction of these systems undergo overflow of their L2 equipotential, in which case we find that stable mass transfer produces merging binary black holes even under extreme assumptions of mass and angular momentum outflows. Our conclusions are limited to the study of one donor mass at a single metallicity, but they suggest that population synthesis calculations overestimate the formation rate of merging binary black holes produced by common-envelope evolution and that stable mass transfer could dominate the formation rate from isolated binaries. This is in agreement with a few other recent studies. Further work is required to extend these results to different masses and metallicities as well as to understand how they can be incorporated into rapid population synthesis calculations.

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Section: Common Envelope In Donors With Convective Envelopessupporting

confidence: 89%

The role of mass transfer and common envelope evolution in the formation of merging binary black holes

Marchant

Pappas

Gallegos-Garcia

et al. 2021

A&A

110

117

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“…The torques by such a disk would also spin the neutron star up, as is the case in Be Xray binaries, but this contradicts the measured long neutron star spin period. An additional strong argument against mass transfer through RLOF comes from the stable orbital period (Falanga et al 2015) because no outflow from the vicinity of the neutron star is observed and conservative mass transfer from a high-mass star to a low-mass accretor would lead to a quickly shrinking orbit (Quast et al 2019;El Mellah et al 2020a). Instead, accretion of the stellar wind is to be preferred as the dominant mass transfer mechanism.…”

Section: Mass Transfer Mechanismsmentioning

confidence: 99%

“…In the case of Vela X-1, the compact object is a neutron star and the secondary has a current mass on the order of 20 M . Consequently, we would expect a primary more massive than that with suggestions going up to 60 M (Quast et al 2019). Given that enough mass needed to be removed to eventually yield a neutron star as the compact object, the latter number might be a bit high, but illustrates the severe uncertainty when trying to extrapolate the systems' backstory.…”

Section: Evolutionary Scenariomentioning

confidence: 99%

“…The remaining secondary in Vela X-1 is classified as "overluminous" (e.g., Wickramasinghe 1975;Conti 1978). This term generally refers to that fact that the object is more luminous than expected for its mass, although the details differ in whether this refers to a simple comparison with single star evolution (e.g., Quast et al 2019) or is also used for remaining discrepancies in the context of binary evolution scenarios (e.g., Vanbeveren et al 1993). Regardless of terminology, it is important to account for the fact that the secondary has been rejuvenated and thus will usually have a different luminosity and temperature compared to a single star of the same spectral type.…”

Section: Evolutionary Scenariomentioning

confidence: 99%

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Revisiting the archetypical wind accretor Vela X-1 in depth

Kretschmar

Mellah

Martínez-Núñez

et al. 2021

A&A

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Context. The Vela X-1 system is one of the best-studied X-ray binaries because it was detected early, has persistent X-ray emission, and a rich phenomenology at many wavelengths. The system is frequently quoted as the archetype of wind-accreting high-mass X-ray binaries, and its parameters are referred to as typical examples. Specific values for these parameters have frequently been used in subsequent studies, however, without full consideration of alternatives in the literature, even more so when results from one field of astronomy (e.g., stellar wind parameters) are used in another (e.g., X-ray astronomy). The issues and considerations discussed here for this specific, very well-known example will apply to various other X-ray binaries and to the study of their physics. Aims. We provide a robust compilation and synthesis of the accumulated knowledge about Vela X-1 as a solid baseline for future studies, adding new information where available. Because this overview is targeted at a broader readership, we include more background information on the physics of the system and on methods than is usually done. We also attempt to identify specific avenues of future research that could help to clarify open questions or determine certain parameters better than is currently possible. Methods. We explore the vast literature for Vela X-1 and on modeling efforts based on this system or close analogs. We describe the evolution of our knowledge of the system over the decades and provide overview information on the essential parameters. We also add information derived from public data or catalogs to the data taken from the literature, especially data from the Gaia EDR3 release. Results. We derive an updated distance to Vela X-1 and update the spectral classification for HD 77518. At least around periastron, the supergiant star may be very close to filling its Roche lobe. Constraints on the clumpiness of the stellar wind from the supergiant star have improved, but discrepancies persist. The orbit is in general very well determined, but a slight difference exists between the latest ephemerides. The orbital inclination remains the least certain factor and contributes significantly to the uncertainty in the neutron star mass. Estimates for the stellar wind terminal velocity and acceleration law have evolved strongly toward lower velocities over the years. Recent results with wind velocities at the orbital distance in the range of or lower than the orbital velocity of the neutron star support the idea of transient wind-captured disks around the neutron star magnetosphere, for which observational and theoretical indications have emerged. Hydrodynamic models and observations are consistent with an accretion wake trailing the neutron star. Conclusions. With its extremely rich multiwavelength observational data and wealth of related theoretical studies, Vela X-1 is an excellent laboratory for exploring the physics of accreting X-ray binaries, especially in high-mass systems. Nevertheless, much room remains to improve the accumulated knowledge. On the observational side, well-coordinated multiwavelength observations and observing campaigns addressing the intrinsic variability are required. New opportunities will arise through new instrumentation, from optical and near-infrared interferometry to the upcoming X-ray calorimeters and X-ray polarimeters. Improved models of the stellar wind and flow of matter should account for the non-negligible effect of the orbital eccentricity and the nonspherical shape of HD 77581. There is a need for realistic multidimensional models of radiative transfer in the UV and X-rays in order to better understand the wind acceleration and effect of ionization, but these models remain very challenging. Improved magnetohydrodynamic models covering a wide range of scales are required to improve our understanding of the plasma-magnetosphere coupling, and they are thus a key factor for understanding the variability of the X-ray flux and the torques applied to the neutron star. A full characterization of the X-ray emission from the accretion column remains another so far unsolved challenge.

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“…Furthermore, any mass loss increases the luminosity-to-mass ratio, thus increasing the Eddington factor. It is therefore not surprising that Quast et al (2019) found the mass-radius exponent in such models to be negative (unless steep H/He-gradients are present in the outermost envelope). They showed that correspondingly, mass transfer due to Roche-lobe overflow is unstable, like in the case of red supergiant donors.…”

Section: Envelope Inflationmentioning

confidence: 99%

Properties of OB star−black hole systems derived from detailed binary evolution models

Langer

Schürmann

Stoll

et al. 2020

A&A

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Context. The recent gravitational wave measurements have demonstrated the existence of stellar mass black hole binaries. It is essential for our understanding of massive star evolution to identify the contribution of binary evolution to the formation of double black holes. Aims. A promising way to progress is investigating the progenitors of double black hole systems and comparing predictions with local massive star samples such as the population in 30 Doradus in the Large Magellanic Cloud (LMC). Methods. To this purpose, we analyse a large grid of detailed binary evolution models at LMC metallicity with initial primary masses between 10 and 40 M , and identify which model systems potentially evolve into a binary consisting of a black hole and a massive main sequence star. We then derive the observable properties of such systems, as well as peculiarities of the OB star component. Results. We find that ∼3% of the LMC late O and early B stars in binaries are expected to possess a black hole companion, when assuming stars with a final helium core mass above 6.6 M to form black holes. While the vast majority of them may be X-ray quiet, our models suggest that these may be identified in spectroscopic binaries, either by large amplitude radial velocity variations ( ∼ > 50 km s −1 ) and simultaneous nitrogen surface enrichment, or through a moderate radial velocity ( ∼ > 10 km s −1 ) and simultaneously rapid rotation of the OB star. The predicted mass ratios are such that main sequence companions could be excluded in most cases. A comparison to the observed OB+WR binaries in the LMC, Be/X-ray binaries, and known massive BH binaries supports our conclusion. Conclusions. We expect spectroscopic observations to be able to test key assumptions in our models, with important implications for massive star evolution in general, and for the formation of double-black hole mergers in particular.

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Mass transfer on a nuclear timescale in models of supergiant and ultra-luminous X-ray binaries

Cited by 41 publications

References 93 publications

The role of mass transfer and common envelope evolution in the formation of merging binary black holes

The role of mass transfer and common envelope evolution in the formation of merging binary black holes

Revisiting the archetypical wind accretor Vela X-1 in depth

Properties of OB star−black hole systems derived from detailed binary evolution models

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