Black hole X-ray transients

Hameury, J. M.; King, Andrew; Lasota, Jarosław

doi:10.1086/168647

Cited by 97 publications

(132 citation statements)

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“…On the contrary, the large variety of outburst shapes (duration and type, outsidein and inside-out) observed in the light curves can be explained by these fluctuations (Hameury et al 2000; Paper I). Schreiber et al (2000) argued that mass-transfer rate variations similar to those observed in AM Her should also be present in dwarf novae.…”

Section: Resultsmentioning

confidence: 99%

“…To solve this problem one could use severals remedies. For example, one could add to the model mass-transfer rate enhancements due to the irradiation of the secondary by the accretion flow (Smak 1999;Hameury et al 2000). We will show below, however, that this is not necessary since taking into account the heating by the stream impact and/or tidal torque dissipation (Paper I) gives very satisfactory results.…”

Section: Model and Parametersmentioning

confidence: 99%

“…Smak 1999Smak , 2000Hameury et al 2000). The brightening of the hot spot, the region where the mass-transfer stream interacts with the outer disc's rim, which is observed near the outburst maxima, should be the result of a mass-transfer rate enhancement.…”

Section: Introductionmentioning

confidence: 99%

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Z Cam stars: A particular response to a general phenomenon

Buat-Ménard¹,

Hameury²,

Lasota³

2001

A&A

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Abstract. We show that the disc instability model can reproduce all the observed properties of Z Cam stars if the energy equation includes heating of the outer disc by the mass-transfer stream impact and by tidal torques and if the mass-transfer rate from the secondary varies by about 30% around the value critical for stability. In particular the magnitude difference between outburst maxima and standstills corresponds to observations, all outbursts are of the inside-out type and can be divided into two classes: long (wide) and short (narrow) outbursts, as observed. Mass transfer rate fluctuations should occur in other dwarf novae but one can exclude variations similar to those observed in magnetic systems (AM Her's and some DQ Her's) and some nova-like systems (VY Scl's), in whicḣ M become very small during low states; these would produce mini-outbursts which, although detectable, have never been observed.

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Section: Resultsmentioning

confidence: 99%

Section: Model and Parametersmentioning

confidence: 99%

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Z Cam stars: A particular response to a general phenomenon

Buat-Ménard¹,

Hameury²,

Lasota³

2001

A&A

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“…A small change in disk density at the end of an outburst increases the outer disk temperature enough to partially ionize hydrogen, which then leads to a rapid rise in the accretion rate into the inner disk and a rebrightening. The exact trigger of the reflare is uncertain-they appear spontaneously in the simulations of Dubus et al (2001), although they do not resemble the observed reflares and they are seen by Hameury et al (2000) where reflares are caused by an increased irradiation of the donor star that causes a superoutburst (so called because their duration is much larger than that of normal outbursts) followed by reflares. The donor star in SAX J1808.4−3658 is observed to be strongly irradiated during quiescence (Homer et al 2001;Burderi et al 2003;) and indeed there are suggestions that it is losing a large amount of mass (di Salvo et al 2008; see however Hartman et al 2008 for criticisms of this strong mass loss scenario in SAX J1808.4 −3658 ).…”

Section: The Origin Of Reflaresmentioning

confidence: 98%

The Reflares and Outburst Evolution in the Accreting Millisecond Pulsar Sax J1808.4–3658: A Disk Truncated Near Co-Rotation?

Patruno

Maitra

Curran

et al. 2016

ApJ

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The accreting millisecond X-ray pulsar SAX J1808.4-3658 shows peculiar low luminosity states known as "reflares" after the end of the main outburst. During this phase the X-ray luminosity of the source varies by up to three orders of magnitude in less than 1-2 days. The lowest X-ray luminosity observed reaches a value of 10 erg s 32 1 -, only a factor of a few brighter than its typical quiescent level. We investigate the 2008 and 2005 reflaring state of SAX J1808.4-3658 to determine whether there is any evidence for a change in the accretion flow with respect to the main outburst. We perform a multiwavelength photometric and spectral study of the 2005 and 2008 reflares with data collected during an observational campaign covering the near-infrared, optical, ultra-violet and X-ray band. We find that the NIR/optical/UV emission, expected to come from the outer accretion disk, shows variations in luminosity over an order of magnitude. The corresponding X-ray luminosity variations are instead much deeper, spanning about 2-3 orders of magnitude. The X-ray spectral state observed during the reflares does not change substantially with X-ray luminosity, indicating a rather stable configuration of the accretion flow. We investigate the most likely configuration of the innermost regions of the accretion flow and we infer an accretion disk truncated at or near the co-rotation radius. We interpret these findings as due to either a strong outflow (due to a propeller effect) or a trapped disk (with limited/no outflow) in the inner regions of the accretion flow.

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“…The DIM accounts well for the observed properties of dwarf novae: recurrence times, outburst durations, and amplitudes, provided that some additional ingredients are included in the model, most notably a change in the viscosity parameter α between the hot and cool branches. Some other effects must be taken into account such as, for example, the truncation of the accretion disc in quiescence as a result of the white dwarf magnetic field or of disc evaporation close to the white dwarf; one must also include the possibility of enhanced mass transfer from the secondary (Hameury et al 2000), even though it is unclear that irradiation of the secondary can lead to a significant increase of the mass-loss rate because the L 1 Lagrangian point is shielded by the accretion disc (Viallet & Hameury 2007.…”

Section: Introductionmentioning

confidence: 99%

Dwarf nova outbursts in intermediate polars

Hameury

Lasota

2017

A&A

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Context. The disc instability model (DIM) has been very successful in explaining the dwarf nova outbursts observed in cataclysmic variables. When, as in intermediate polars, the accreting white dwarf is magnetised, the disc is truncated at the magnetospheric radius, but for mass-transfer rates corresponding to the thermal-viscous instability such systems should still exhibit dwarf-nova outbursts. Yet, the majority of intermediate polars, in which the magnetic field is not large enough to completely disrupt the accretion disc, seem to be stable, and the rare observed outbursts, in particular in systems with long orbital periods, are much shorter than normal dwarf-nova outbursts. Aims. We investigate the predictions of the disc instability model for intermediate polars in order to determine which of the observed properties of these systems can be explained by the DIM. Methods. We use our numerical code for the time evolution of accretion discs, modified to include the effects of the magnetic field, with constant or variable mass transfer from the secondary star. Results. We show that intermediate polars have mass transfer low enough and magnetic fields large enough to keep the accretion disc stable on the cold equilibrium branch. We show that the infrequent and short outbursts observed in long-period systems, such as, for example, TV Col, cannot be attributed to the thermal-viscous instability of the accretion disc, but instead have to be triggered by an enhanced mass-transfer from the secondary, or, more likely, by some instability coupling the white dwarf magnetic field with that generated by the magnetorotational instability operating in the accretion disc. Longer outbursts (a few days) could result from the disc instability.

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Black hole X-ray transients

Cited by 97 publications

References 0 publications

Z Cam stars: A particular response to a general phenomenon

Z Cam stars: A particular response to a general phenomenon

The Reflares and Outburst Evolution in the Accreting Millisecond Pulsar Sax J1808.4–3658: A Disk Truncated Near Co-Rotation?

Dwarf nova outbursts in intermediate polars

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