Modeling of non-stationary accretion disks in X-ray novae A 0620–00 and GRS 1124–68 during outburst

Suleimanov, V.; Lipunova, G. V.; Шакура, Н. И.

doi:10.1051/0004-6361:200810155

Cited by 36 publications

(38 citation statements)

References 74 publications

(117 reference statements)

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“…Another possibility is to make use of a combination of optical and Xray light-curves of these systems. Here, constraints on C irr can be derived by computing the fraction of X-ray emission needed to be reprocessed to explain the observed optical luminosity (e.g., see Suleimanov et al 2008;Lipunova & Malanchev 2017). A third possibility involves using the correlation between X-ray and optical variability often observed in LMXBs to understand physical properties of the different components (i.e.…”

Section: Discussionmentioning

confidence: 99%

Understanding X-ray irradiation in low-mass X-ray binaries directly from their light-curves

Tetarenko

Dubus

Lasota

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The X-ray light-curves of the recurring outbursts observed in low-mass X-ray binaries provide strong test beds for constraining (still) poorly understood disc-accretion processes. These light-curves act as a powerful diagnostic to probe the physics behind the mechanisms driving mass inflow and outflow in these binary systems. We have thus developed an innovative methodology, combining a foundation of Bayesian statistics, observed X-ray light-curves, and accretion disc theory. With this methodology, we characterize the angular-momentum (and mass) transport processes in an accretion disc, as well as the properties of the X-ray irradiation-heating that regulates the decay from outburst maximum in low-mass X-ray transients. We recently applied our methodology to the Galactic black-hole low-mass X-ray binary population, deriving from their lightcurves the first-ever quantitative measurements of the α-viscosity parameter in these systems (Tetarenko et al. 2018). In this paper, we continue the study of these binaries, using Bayesian methods to investigate the X-ray irradiation of their discs during outbursts of strong accretion. We find that the predictions of the discinstability model, assuming a source of X-ray irradiation proportional to the central accretion rate throughout outburst, do not adequately describe the later stages of BH-LMXB outburst light-curves. We postulate that the complex and varied light-curve morphology observed across the population is evidence for irradiation that varies in time and space within the disc, throughout individual transient outbursts. Lastly, we demonstrate the robustness of our methodology, by accurately reproducing the synthetic model light-curves computed from numerical codes built to simulate accretion flows in binary systems.

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Section: Discussionmentioning

confidence: 99%

Understanding X-ray irradiation in low-mass X-ray binaries directly from their light-curves

Tetarenko

Dubus

Lasota

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…However, semi-analytical and numerical simulations (see, for example, Masada & Sano 2008;Stone 2011;Hawley et al 2013;Suzuki & Inutsuka 2014;Nauman & Blackman 2015) suggest that the total (Reynolds + Maxwell) stresses due to MRI are insufficient to cause the effective angular momentum transfer in accretion discs in terms of the phenomenological alpha-parameter α S S (Shakura & Sunyaev 1973), giving rather low values α S S ∼ 0.01 − 0.03. Note that from the observational point of view, the alpha-parameter can be reliably evaluated, e.g., from the analysis of non-stationary accretion discs in X-ray novae (Suleimanov, Lipunova & Shakura 2008), dwarf-nova and AM CVn stars (Kotko & Lasota 2012), and turns out to be an order of magnitude higher than typically found in the numerical MRI simulations.…”

Section: Introductionmentioning

confidence: 97%

On properties of Velikhov–Chandrasekhar MRI in ideal and non-ideal plasma

Шакура¹,

Постнов²

2015

Monthly Notices of the Royal Astronomical Society

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Conditions of Velikhov-Chandrasekhar magneto-rotational instability in ideal and non-ideal plasmas are examined. Linear WKB analysis of hydromagnetic axially symmetric flows shows that in the Rayleigh-unstable hydrodynamic case where the angular momentum decreases with radius, the MRI branch becomes stable, and the magnetic field suppresses the Rayleigh instability at small wavelengths. We investigate the limiting transition from hydromagnetic flows to hydrodynamic flows. The Rayleigh mode smoothly transits to the hydrodynamic case, while the Velikhov-Chandrasekhar MRI mode completely disappears without the magnetic field. The effects of viscosity and magnetic diffusivity in plasma on the MRI conditions in thin accretion discs are studied. We find the limits on the mean free-path of ions allowing MRI to operate in such discs.

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“…The size of the hot part of the disk depends on the radial temperature distribution, meanwhile the disk temperature depends on the viscous heating rate and the incident flux of central X-rays. Previously, Suleimanov et al (2008) have analysed X-ray and optical lightcurves of A 0620-00 (1975) and GS 1124GS -68 (1991, which have The left panels show the disk-to-total-flux ratio in 0.5 − 50 keV and reduced χ 2 . Empty circles denote the spectral fits made with the fixed distance ≈ 8.62 kpc, which has been found as the average for the observations at moments when the distance is least variable (before MJD 52456).…”

Section: Introductionmentioning

confidence: 99%

Determination of the turbulent parameter in accretion discs: effects of self-irradiation in 4U 1543−47 during the 2002 outburst

Lipunova

Malanchev

2017

Monthly Notices of the Royal Astronomical Society

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We investigate the viscous evolution of the accretion disk in 4U 1543−47, a black hole binary system, during the first 30 days after the peak of the 2002 burst by comparing the observed and theoretical accretion rate evolutionṀ(t). The observedṀ(t) is obtained from spectral modelling of the archival RXTE/PCA data. Different scenarios of disk decay evolution are possible depending on a degree of self-irradiation of the disk by the emission from its centre. If the self-irradiation, which is parametrized by factor C irr , had been as high as ∼ 5 × 10 −3 , then the disk would have been completely ionized up to the tidal radius and the short time of the decay would have required the turbulent parameter α ∼ 3. We find that the shape of theṀ(t) curve is much better explained in a model with a shrinking high-viscosity zone. If C irr ≈ (2 − 3) × 10 −4 , the resulting α lie in the interval 0.5 − 1.5 for the black hole masses in the range 6 − 10 M , while the radius of the ionized disk is variable and controlled by irradiation. For very weak irradiation, C irr < 1.5 × 10 −4 , the burst decline develops as in normal outbursts of dwarf novae with α ∼ 0.08 − 0.32. The optical data indicate that C irr in 4U 1543−47 (2002) was not greater than approximately (3−6)×10 −4 . Generally, modelling of an X-ray nova burst allows one to estimate α that depends on the black hole parameters. We present the public 1-D code freddi to model the viscous evolution of an accretion disk. Analytic approximations are derived to estimate α in X-ray novae usingṀ(t).

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Modeling of non-stationary accretion disks in X-ray novae A 0620–00 and GRS 1124–68 during outburst

Cited by 36 publications

References 74 publications

Understanding X-ray irradiation in low-mass X-ray binaries directly from their light-curves

Understanding X-ray irradiation in low-mass X-ray binaries directly from their light-curves

On properties of Velikhov–Chandrasekhar MRI in ideal and non-ideal plasma

Determination of the turbulent parameter in accretion discs: effects of self-irradiation in 4U 1543−47 during the 2002 outburst

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