Stability of radiation-pressure dominated disks

Ciesielski, Adam; Wielgus, Maciek; Kluźniak, W.; Sądowski, Aleksander; Abramowicz, Marek A.; Lasota, Jean–Pierre; Rebusco, P.

doi:10.1051/0004-6361/201117478

Cited by 20 publications

(19 citation statements)

References 15 publications

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“…Recently, linear stability analyses have been conducted that allow the pressure to lag behind stress, and vice versa. These show that, despite this impediment, instability can in fact persist, especially with the short time‐lags witnessed in our simulations (Lin, Gu & Lu ; Ciesielski et al ). It would appear then that the main obstacle to instability in turbulent models of discs is due to something else, perhaps the stochastic nature of the viscous stress which is not faithfully reproduced in the behaviour of the volume‐averaged pressure (Janiuk & Misra ).…”

Section: Numerical Resultssupporting

confidence: 63%

Hysteresis and thermal limit cycles in MRI simulations of accretion discs

Latter

Papaloizou

2012

Monthly Notices of the Royal Astronomical Society

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The recurrent outbursts that characterize low-mass binary systems reflect thermal state changes in their associated accretion discs. The observed outbursts are connected to the strong variation in disc opacity as hydrogen ionizes near 5000 K. This physics leads to accretion disc models that exhibit bistability and thermal limit cycles, whereby the disc jumps between a family of cool and low-accreting states and a family of hot and efficiently accreting states. Previous models have parametrized the disc turbulence via an alpha (or 'eddy') viscosity. In this paper we treat the turbulence more realistically via a suite of numerical simulations of the magnetorotational instability (MRI) in local geometry. Radiative cooling is included via a simple but physically motivated prescription. We show the existence of bistable equilibria and thus the prospect of thermal limit cycles, and in so doing demonstrate that MRI-induced turbulence is compatible with the classical theory. Our simulations also show that the turbulent stress and pressure perturbations are only weakly dependent on each other on orbital times; as a consequence, thermal instability connected to variations in turbulent heating (as opposed to radiative cooling) is unlikely to operate, in agreement with previous numerical results. Our work presents a first step towards unifying simulations of full magnetohydrodynamic turbulence with the correct thermal and radiative physics of the outbursting discs associated with dwarf novae, low-mass X-ray binaries and possibly young stellar objects.

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Section: Numerical Resultssupporting

confidence: 63%

Hysteresis and thermal limit cycles in MRI simulations of accretion discs

Latter

Papaloizou

2012

Monthly Notices of the Royal Astronomical Society

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“…This discovery started a long debate, which continues unresolved to this day. A recent update is provided in [60].…”

Section: Thermal and Viscous Instabilitymentioning

confidence: 99%

Foundations of Black Hole Accretion Disk Theory

Abramowicz

Fragile

2013

Living Rev. Relativ.

597

488

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This review covers the main aspects of black hole accretion disk theory. We begin with the view that one of the main goals of the theory is to better understand the nature of black holes themselves. In this light we discuss how accretion disks might reveal some of the unique signatures of strong gravity: the event horizon, the innermost stable circular orbit, and the ergosphere. We then review, from a first-principles perspective, the physical processes at play in accretion disks. This leads us to the four primary accretion disk models that we review: Polish doughnuts (thick disks), Shakura-Sunyaev (thin) disks, slim disks, and advection-dominated accretion flows (ADAFs). After presenting the models we discuss issues of stability, oscillations, and jets. Following our review of the analytic work, we take a parallel approach in reviewing numerical studies of black hole accretion disks. We finish with a few select applications that highlight particular astrophysical applications: measurements of black hole mass and spin, black hole vs. neutron star accretion disks, black hole accretion disk spectral states, and quasi-periodic oscillations (QPOs).

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“…It reasonably introduces a time-delay between the viscous stress and total pressure, but this delay vanishes in the alpha-prescription. Our colleagues Lin et al (2011) and Ciesielski et al (2012) have focused on the effects of this time-delay on thermal instability and they conclude that it can not remarkably diminish or remove the instability for typical delay lengths. Indeed, in this work, we find and investigate the other effect of this delay on the oscillation of accretion discs (please concern our paper in ApJLett for the detail).…”

Section: Resultsmentioning

confidence: 99%

P-mode oscillation on slim discs

Xue¹,

Lu²

2014

Proc. IAU

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Abstract. We numerically investigate the thermally unstable accretion discs around spinning black holes with different spins. We adopted an additional evolutionary viscosity equation to replace the standard alpha-prescription based on the results of two MHD simulations. We find an interesting oscillation when accretion switches to slim disc mode. The oscillation arises from the sonic point of accretion flow and propagates outwards. We mimic the bolometric light-curve and find a series of harmonics on its power spectrum. The frequency ratio of those harmonics is a regular integer series. The lowest frequency of the harmonics is identical to the prediction of trapped p-mode in QPO theory.

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Stability of radiation-pressure dominated disks

Cited by 20 publications

References 15 publications

Hysteresis and thermal limit cycles in MRI simulations of accretion discs

Hysteresis and thermal limit cycles in MRI simulations of accretion discs

Foundations of Black Hole Accretion Disk Theory

P-mode oscillation on slim discs

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