Three-dimensional hydrodynamic Bondi-Hoyle accretion. 2: Homogeneous medium at Mach 3 with gamma = 5/3

Ruffert, M.; Arnett, David

doi:10.1086/174145

Cited by 125 publications

(136 citation statements)

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“…As has been demonstrated in previous numerical simulations, in the zerogradient case Ṁ HL provides a good order-of-magnitude estimate of the accretion rate (e.g., Ruffert 1994a; Ruffert & Arnett 1994;Naiman et al 2011;Blondin & Raymer 2012). As the upstream density gradient steepens, the steady state accretion rate drops precipitously.…”

Section: Accretion Of Mass and Angular Momentumsupporting

confidence: 70%

“…Blondin & Raymer (2012) study two different accretor sizes with g = 5 3 and  = ¥ 3 to find extremely stable accretion with the larger accretor (with radius 5% of the accretion radius), but a breathing mode instability and some variation in accretion rate with an accretor of only 1% of R a . Very little loss of axisymmetry is observed in these simulations, however, with differences as compared to Ruffert & Arnett (1994) potentially attributable to differences in grid meshing and resolution.…”

Section: Previous Numerical Studies Of Hlamentioning

confidence: 78%

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Asymmetric Accretion Flows Within a Common Envelope

MacLeod

Ramírez-Ruiz

2015

ApJ

128

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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: Accretion Of Mass and Angular Momentumsupporting

confidence: 70%

Section: Previous Numerical Studies Of Hlamentioning

confidence: 78%

Asymmetric Accretion Flows Within a Common Envelope

MacLeod

Ramírez-Ruiz

2015

ApJ

128

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“…The eigenmodes corresponding to this unstable cycle will be investigated in the second paper of this series (Foglizzo 2001). The fact that the most unstable simulations of Bondi-Hoyle-Lyttleton accretion also correspond to γ = 5/3 (Ruffert & Arnett 1994, Ruffert 1994b) already encourages us to look for an extrapolation of these results to the case of non-radial shocked accretion flows.…”

Section: Discussionmentioning

confidence: 99%

Entropic-acoustic instability of shocked Bondi accretion I. What does perturbed Bondi accretion sound like?

Foglizzo

2001

A&A

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Abstract. In the radial flow of gas into a black hole (i.e. Bondi accretion), the infall of any entropy or vorticity perturbation produces acoustic waves propagating outward. The dependence of this acoustic flux on the shape of the perturbation is investigated in detail. This is the key process in the mechanism of the entropic-acoustic instability proposed by Foglizzo& Tagger (2000) to explain the instability of Bondi-Hoyle-Lyttleton accretion. These acoustic waves create new entropy and vorticity perturbations when they reach the shock, thus closing the entropicacoustic cycle. With an adiabatic index 1 < γ ≤ 5/3, the linearized equations describing the perturbations of the Bondi flow are studied analytically and solved numerically. The fundamental frequency of this problem is the cut-off frequency of acoustic refraction, below which ingoing acoustic waves are refracted out. This cut-off is significantly smaller than the Keplerian frequency at the sonic radius and depends on the latitudinal number l of the perturbations.When advected adiabatically inward, entropy and vorticity perturbations trigger acoustic waves propagating outward, with an efficiency which is highest for non radial perturbations l = 1. The outgoing acoustic flux produced by the advection of vorticity perturbations is always moderate and peaks at rather low frequency. By contrast, the acoustic flux produced by an entropy wave is highest close to the refraction cut-off. It can be very large if γ is close to 5/3. These results suggest that the shocked Bondi flow with γ = 5/3 is strongly unstable with respect to the entropic-acoustic mechanism.

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“…In general, 3D simulations increase the instabilities and fluctuations. These effects have been studied in the idealized case of Hoyle-Lyttleton accretion (Taam & Fryxell 1988;Ruffert 1999;Blondin & Raymer 2012) and in accreting pulsars where a formation of a planar accretion disk is expected from 2D codes, whilst accretion in 3D is unstable, allowing the formation of filamentary structures (Ruffert & Arnett 1994).…”

Section: The Hydrodynamical Codementioning

confidence: 99%

Neutron star masses from hydrodynamical effects in obscured supergiant high mass X-ray binaries

Manousakis

Walter

Blondin

2012

A&A

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Context. A population of obscured supergiant high mass X-ray binaries has been discovered by INTEGRAL. X-ray wind tomography of IGR J17252-3616 inferred a slow wind velocity to account for the enhanced obscuration. Aims. The main goal of this study is to understand under which conditions high obscuration could occur. Methods. We have used an hydrodynamical code to simulate the flow of the stellar wind around the neutron star. A grid of simulations was used to study the dependency of the absorbing column density and of the X-ray light-curves on the model parameters. A comparison between the simulation results and the observations of IGR J17252-3616 provides an estimate on these parameters. Results. We have constrained the wind terminal velocity to 500−600 km s −1 and the neutron star mass to 1.75−2.15 M . Conclusions. We have confirmed that the initial hypothesis of a slow wind velocity with a moderate mass loss rate is valid. The mass of the neutron star can be constrained by studying its impact on the accretion flow.

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Three-dimensional hydrodynamic Bondi-Hoyle accretion. 2: Homogeneous medium at Mach 3 with gamma = 5/3

Cited by 125 publications

References 0 publications

Asymmetric Accretion Flows Within a Common Envelope

Asymmetric Accretion Flows Within a Common Envelope

Entropic-acoustic instability of shocked Bondi accretion I. What does perturbed Bondi accretion sound like?

Neutron star masses from hydrodynamical effects in obscured supergiant high mass X-ray binaries

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