On the Wind-driven Relaxation Cycle in Accretion Disks

Ganguly, Shalini; Proga, Daniel

doi:10.3847/1538-4357/ab6aa0

Cited by 7 publications

(5 citation statements)

References 29 publications

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“…The oscillation periods predicted by Shields et al (1986) are comparable to those observed in GRS 1915+105, but the source appears to be an order of magnitude below the critical Ṁwind / Ṁacc threshold. A recent numerical study by Ganguly & Proga (2020) has found that oscillations manifest at lower ratios, perhaps even at Ṁwind / Ṁacc ≃ 6. Our estimate of the loss rate would approach this threshold if the wind was launched vertically.…”

Section: Discussionmentioning

confidence: 99%

An Obscured, Seyfert-2-like State of the Stellar-mass Black Hole GRS 1915+105 Caused by Failed Disk Winds

Miller,

Zoghbi,

Raymond

et al. 2020

Preprint

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We report on Chandra gratings spectra of the stellar-mass black hole GRS 1915+105 obtained during a novel, highly obscured state. As the source entered this state, a dense, massive accretion disk wind was detected through strong absorption lines. Photionization modeling indicates that it must originate close to the central engine, orders of magnitude from the outer accretion disk. Strong, nearly sinusoidal flux variability in this phase yielded a key insight: the wind is blue-shifted when its column density is relatively low, but red-shifted as it approaches the Compton-thick threshold. At no point does the wind appear to achieve the local escape velocity; in this sense, it is a "failed wind." Later observations suggest that the disk ultimately fails to keep even the central engine clear of gas, leading to heavily obscured and Compton-thick states characterized by very strong Fe K emission lines. Indeed, these later spectra are successfully described using models developed for obscured AGN. We discuss our results in terms the remarkable similarity of GRS 1915+105 deep in its "obscured state" to Seyfert-2 and Compton-thick AGN, and explore how our understanding of accretion and obscuration in massive black holes is impacted by our observations.

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Section: Discussionmentioning

confidence: 99%

An Obscured, Seyfert-2-like State of the Stellar-mass Black Hole GRS 1915+105 Caused by Failed Disk Winds

Miller,

Zoghbi,

Raymond

et al. 2020

Preprint

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“…Accretion disk winds can also be launched from the outer disk via thermal driving, and this process could be important in creating the central X-ray corona and regulating the overall mass accretion rate through the disk (Shakura & Sunyaev 1973;Begelman et al 1983;Shields et al 1986). However, new numerical simulations suggest that the regulating effects of a wind are likely to be more modest (Ganguly & Proga 2020).…”

Section: Introductionmentioning

confidence: 99%

Swift Spectroscopy of the Accretion Disk Wind in the Black Hole GRO J1655–40

Balakrishnan

Miller

Trueba

et al. 2020

ApJ

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Chandra obtained two High Energy Transmission Grating (HETG) spectra of the stellar-mass black hole GRO J1655−40 during its 2005 outburst, revealing a rich and complex disk wind. Soon after its launch, the Neil Gehrels Swift Observatory began monitoring the same outburst. Some X-ray Telescope (XRT) observations were obtained in a mode that makes it impossible to remove strong Mn calibration lines, so the Fe Kα line region in the spectra was previously neglected. However, these lines enable a precise calibration of the energy scale, facilitating studies of the absorption-dominated disk wind and its velocity shifts. Here, we present fits to 15 Swift/XRT spectra, revealing variability and evolution in the outflow. The data strongly point to a magnetically driven disk wind: both the higher velocity (e.g., v ≃ 10 4 km s −1 ) and lower velocity (e.g., v ≃ 10 3 km s −1 ) wind components are typically much faster than is possible for thermally driven outflows (v ≤ 200 km s −1 ), and photoionization modeling yields absorption radii that are two orders of magnitude below the Compton radius that defines the typical inner extent of thermal winds. Moreover, correlations between key wind parameters yield an average absorption measure distribution (AMD) that is consistent with magnetohydrodynamic wind models. We discuss our results in terms of recent observational and theoretical studies of black hole accretion disks and outflows, and future prospects.

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“…This is an interesting possibility, however, the light curves generated by such an instability do not, and cannot resemble, even remotely what is observed in HLX-1 (see e.g. Shields et al 1986;Ganguly & Proga 2020).…”

Section: Hlx-1 In Eso 243-49mentioning

confidence: 92%

Models of Ultra-Luminous X-ray transient sources

Hameury,

Lasota

2020

Preprint

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Context. It is now widely accepted that most ultraluminous X-ray sources (ULXs) are binary systems whose large (above 10 39 erg s −1 ) apparent luminosities are explained by super-Eddington accretion onto a stellar-mass compact object. Many of the ULXs, especially those containing magnetized neutron stars, are highly variable; some exhibit transient behaviour. Large luminosities might imply large accretion discs that could be therefore prone to the thermal-viscous instability known to drive outbursts of dwarf novae and low-mass X-ray binary transient sources.Aims. The aim of this paper is to extend and generalize the X-ray transient disc-instability model to the case of large (outer radius larger than 10 12 cm) accretion discs and apply it to the description of systems with super-Eddington accretion rates at outburst and, in some cases, super-Eddington mass transfer rates. Methods. We have used our disc-instability-model code to calculate the time evolution of the accretion disc and the outburst properties. Results. We show that, provided that self-irradiation of the accretion disc is efficient even when the accretion rate exceeds the Eddington value, possibly due to scattering back of the X-ray flux emitted by the central parts of the disc on the outer portions of the disc, heating fronts can reach the disc's outer edge generating high accretion rates. We also provide analytical approximations for the observable properties of the outbursts. We have reproduced successfully the observed properties of galactic transients with large discs, such as V404 Cyg, as well as some ULXs such as M51 XT-1. Our model can reproduce the peak luminosity and decay time of ESO 243-39 HLX-1 outbursts if the accretor is a neutron star. Conclusions. Observational tests of our predicted relations between the outburst duration and decay time with peak luminosity would be most welcome.

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On the Wind-driven Relaxation Cycle in Accretion Disks

Cited by 7 publications

References 29 publications

An Obscured, Seyfert-2-like State of the Stellar-mass Black Hole GRS 1915+105 Caused by Failed Disk Winds

An Obscured, Seyfert-2-like State of the Stellar-mass Black Hole GRS 1915+105 Caused by Failed Disk Winds

Swift Spectroscopy of the Accretion Disk Wind in the Black Hole GRO J1655–40

Models of Ultra-Luminous X-ray transient sources

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