Black holes in X-ray binaries - Marginal existence and rotation reversals of accretion disks

Shapiro, S. L.; Lightman, Alan P.

doi:10.1086/154203

Cited by 129 publications

(115 citation statements)

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“…This work builds on analytic considerations (Dodd & McCrea 1952;Illarionov & Sunyaev 1975;Shapiro & Lightman 1976;Davies & Pringle 1980) and simulations of nonaxisymmetric flow conditions in HLA (Soker & Livio 1984;Soker et al 1986;Livio et al 1986a;Fryxell & Taam 1988;Ruffert 1999). However, since much of this work was motivated by inhomogeneities in wind-capture binaries, typical density gradients tend to be much milder than those experienced by an embedded object within a CE.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Accretion Flows Within a Common Envelope

MacLeod

Ramírez-Ruiz

2015

ApJ

126

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This paper examines flows in the immediate vicinity of stars and compact objects dynamically inspiralling within a common envelope (CE). Flow in the vicinity of the embedded object is gravitationally focused, leading to drag and potentially to gas accretion. This process has been studied numerically and analytically in the context of HoyleLyttleton accretion (HLA). Yet, within a CE, accretion structures may span a large fraction of the envelope radius, and in so doing sweep across a substantial radial gradient of density. We quantify these gradients using detailed stellar evolution models for a range of CE encounters. We provide estimates of typical scales in CE encounters that involve main sequence stars, white dwarfs, neutron stars, and black holes with giant-branch companions of a wide range of masses. We apply these typical scales to hydrodynamic simulations of three-dimensional HLA with an upstream density gradient. This density gradient breaks the symmetry that defines HLA flow, and imposes an angular momentum barrier to accretion. Material that is focused into the vicinity of the embedded object thus may not be able to accrete. As a result, accretion rates drop dramatically, by one to two orders of magnitude, while drag rates are only mildly affected. We provide fitting formulae to the numerically derived rates of drag and accretion as a function of the density gradient. The reduced ratio of accretion to drag suggests that objects that can efficiently gain mass during CE evolution, such as black holes and neutron stars, may grow less than implied by the HLA formalism.

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Section: Introductionmentioning

confidence: 99%

Asymmetric Accretion Flows Within a Common Envelope

MacLeod

Ramírez-Ruiz

2015

ApJ

126

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“…Estimates have been made by different authors (see, e.g., Illarionov & Sunyaev 1975;Shapiro & Lightman 1976;Wang 1981;Ruffert 1997) under some simplyfing hypothesis which might not apply in our case. However, we can take as a reasonable upper limit the value j w ∼ ΩR …”

Section: Discussionmentioning

confidence: 70%

Discovery of spin-up in the X-ray pulsar companion of the hot subdwarf HD 49798

Mereghetti

Pintore

Esposito

et al. 2016

Mon. Not. R. Astron. Soc.

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The hot subdwarf HD 49798 has an X-ray emitting compact companion with a spin-period of 13.2 s and a dynamically measured mass of 1.28±0.05 M , consistent with either a neutron star or a white dwarf. Using all the available XMM-Newton and Swift observations of this source, we could perform a phase-connected timing analysis extending back to the ROS AT data obtained in 1992. We found that the pulsar is spinning up at a rate of (2.15±0.05)×10 −15 s s −1 . This result is best interpreted in terms of a neutron star accreting from the wind of its subdwarf companion, although the remarkably steady period derivative over more than 20 years is unusual in wind-accreting neutron stars. The possibility that the compact object is a massive white dwarf accreting through a disk cannot be excluded, but it requires a larger distance and/or properties of the stellar wind of HD 49798 different from those derived from the modelling of its optical/UV spectra.

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“…Third, the accretion disk or stellar wind fluorescence should produce cross-correlation functions very different from those in Figure 3. Since the outer disk radius is only a small fraction of the black hole Roche lobe size (Shapiro & Lightman 1976), the time delay of the fluorescent disk emission is much shorter than that in Figure 3. In the case of stellar wind fluorescence, time delays should be distributed in the broad range Dt ≈ r/c around the average value , where r is the characteristic t ϭ r/c radius of the fluorescence region.…”

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confidence: 82%

A Method of Mass Measurement in Black Hole Binaries using Timing and High-Resolution X-Ray Spectroscopy

Vikhlinin

1999

The Astrophysical Journal

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In X-ray binaries, several percent of the compact object luminosity is intercepted by the surface of the normal companion and reradiated through Compton reflection and the K fluorescence. This reflected emission follows the variability of the compact object with a delay approximately equal to the orbital radius divided by the speed of light. This provides the possibility of measuring the orbital radius and thus substantially refining the compact object mass determination compared to using optical data alone. We demonstrate that it may be feasible to measure the time delay between the direct and reflected emission using cross-correlation of the light curves observed near the Ka line and above the K edge of neutral iron. In the case of Cygnus X-1, the time delay measurement is feasible with a -10 6 s observation by a telescope with a 1000 cm 2 effective area near 6.4 keV and with 5 3 # 10 a ∼5 eV energy resolution. With longer exposures, it may be possible to obtain mass constraints even if an Xray source in the binary system lacks an optical counterpart.

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Black holes in X-ray binaries - Marginal existence and rotation reversals of accretion disks

Cited by 129 publications

References 0 publications

Asymmetric Accretion Flows Within a Common Envelope

Asymmetric Accretion Flows Within a Common Envelope

Discovery of spin-up in the X-ray pulsar companion of the hot subdwarf HD 49798

A Method of Mass Measurement in Black Hole Binaries using Timing and High-Resolution X-Ray Spectroscopy

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