An Accretion Disk-Outflow Model for Hysteretic State Transition in X-Ray Binaries

Cao, Xinwu

doi:10.3847/0004-637x/817/1/71

Cited by 36 publications

(29 citation statements)

References 60 publications

(91 reference statements)

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“…The field internally generated in the ADAF will decay after the transition to a thin accretion disc. Estimates of the state transition timescale and the field diffusion time scale in the thin disc show these two timescales are roughly comparable (Cao 2016a;Cao & Lai 2019), which implies that the jets will be soon switched off after the hard-to-soft state transition.…”

Section: The Nature Of the Hard Statementioning

confidence: 94%

Jets in the soft state in Cyg X-3 caused by advection of the donor magnetic field and unification with low-mass X-ray binaries

Cao

Zdziarski

2019

Monthly Notices of the Royal Astronomical Society

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The high-mass accreting binary Cyg X-3 is distinctly different from low-mass X-ray binaries (LMXBs) in having powerful radio and γ-ray emitting jets in its soft spectral state. However, the transition from the hard state to the soft one is first associated with quenching of the hardstate radio emission, as in LMXBs. The powerful soft-state jets in Cyg X-3 form, on average, ∼50 d later. We interpret the initial jet quenching as due to the hard-state vertical magnetic field quickly diffusing away in the thin disc extending to the innermost stable circular orbit in the soft state, or, if that field is produced in situ, also cessation of its generation. The subsequent formation of the powerful jets occurs due to advection of the magnetic field from the donor. We find this happens only above certain threshold accretion rate associated with appearance of magnetically driven outflows. The ∼50 d lag is of the order of the viscous timescale in the outer disc, while the field advection is much faster. This process does not happen in LMXBs due to the magnetic fluxes available from their donors being lower than that for the wind accretion from the Wolf-Rayet donor of Cyg X-3. In our model, the vertical magnetic field in the hard state, required to form the jets both in Cyg X-3 and LMXBs, is formed in situ rather than advected from the donor. Our results provide a unified scenario of the soft and hard states in both Cyg X-3 and LMXBs.

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Section: The Nature Of the Hard Statementioning

confidence: 94%

Jets in the soft state in Cyg X-3 caused by advection of the donor magnetic field and unification with low-mass X-ray binaries

Cao

Zdziarski

2019

Monthly Notices of the Royal Astronomical Society

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“…The uncertainty is caused by our poor understanding of disc evaporation mechanisms. In the hard state, a number of different mechanisms to keep the disc truncated and change R in with changing luminosity and source history (including a hysteretic behaviour of state transitions) have been proposed, e.g., Meyer-Hofmeister, Liu & Meyer (2005), Petrucci et al (2008), Begelman & Armitage (2014), Kylafis & Belloni (2015), Cao (2016). We conclude that the correct theoretical dependence of R in on the time and luminosity after the onset of an outburst in the hard and intermediate states remains unknown.…”

Section: Introductionmentioning

confidence: 99%

Comparison of spectral models for disc truncation in the hard state of GX 339–4

Dziełak

Zdziarski

Szanecki

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We probe models of disc truncation in the hard spectral state of an outburst of the well-known X-ray transient GX 339-4. We test a large number of different models of disc reflection and its relativistic broadening, using two independent sets of codes, and apply it to a Rossi X-ray Timing Explorer spectrum in the rising part of the hard state of the 2010/11 outburst. We find our results to be significantly model-dependent. While all of the models tested show best-fits consistent with truncation, some models allow the disc to extend close to the innermost stable circular orbit (ISCO) and some require substantial disc truncation. The different models yield a wide range in best-fit values for the disc inclination. Our statistically best model has a physical thermal Comptonization primary continuum, requires the disc to be truncated at a radius larger than or equal to about two ISCO radii for the maximum dimensionless spin of 0.998, and predicts a disc inclination in agreement with that of the binary. Our preferred models have moderate Fe abundance, 2 times solar. We have also tested the effect of increasing the density of the reflecting medium. We find it leads to an increase in the truncation radius, but also to an increase in the Fe abundance, opposite to a previous finding.

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“…Many such mechanisms have been proposed (see e.g. Begelman & Armitage 2014;Nixon & Salvesen 2014;Cao 2016, for recent examples); they are clearly disconnected from the DIM.…”

Section: The Case Of Lmxbsmentioning

confidence: 99%

Hystereses in dwarf nova outbursts and low-mass X-ray binaries

Hameury

Lasota

Knigge

et al. 2017

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Context. The disc instability model (DIM) successfully explains why many accreting compact binary systems exhibit outbursts, during which their luminosity increases by orders of magnitude. The DIM correctly predicts which systems should be transient and works regardless of whether the accretor is a black hole, a neutron star or a white dwarf. However, it has been known for some time that the outbursts of X-ray binaries (which contain neutron-star or black-hole accretors) exhibit hysteresis in the X-ray hardness-intensity diagram (HID). More recently, it has been shown that the outbursts of accreting white dwarfs also show hysteresis, but in a diagram combining optical, EUV and X-ray fluxes. Aims. We examine here the nature of the hysteresis observed in cataclysmic variables and low-mass X-ray binaries. Methods. We use the Hameury et al. (1998) code for modelling dwarf nova outbursts, and construct the hardness intensity diagram as predicted by the disc instability model. Results. We show explicitly that the standard DIM -modified only to account for disc truncation -can explain the hysteresis observed in accreting white dwarfs, but cannot explain that observed in X-ray binaries. Conclusions. The spectral evidence for the existence of different accretion regimes / components (disc, corona, jets, etc.) should be based only on wavebands that are specific to the innermost parts of the discs, i.e. EUV and X-rays, which is a difficult task because of interstellar absorption. The existing data, however, indicate that an EUV/X-ray hysteresis is present in SS Cyg.

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An Accretion Disk-Outflow Model for Hysteretic State Transition in X-Ray Binaries

Cited by 36 publications

References 60 publications

Jets in the soft state in Cyg X-3 caused by advection of the donor magnetic field and unification with low-mass X-ray binaries

Jets in the soft state in Cyg X-3 caused by advection of the donor magnetic field and unification with low-mass X-ray binaries

Comparison of spectral models for disc truncation in the hard state of GX 339–4

Hystereses in dwarf nova outbursts and low-mass X-ray binaries

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