Formation of Magnetically Supported Disks during Hard-to-Soft Transitions in Black Hole Accretion Flows

Machida, Mami; Nakamura, Kenji; Matsumoto, Ryoji

doi:10.1093/pasj/58.1.193

Cited by 91 publications

(168 citation statements)

References 44 publications

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“…Such attempts have been so far conducted on many occassions (e.g. Giannios & Spruit 2004;Machida et al 2006;Machida & Matsumoto 2008). Fundamental and dynamical Fourier analysis of X-ray light curves gained a leading position in spoting the existence and evolution of QPOs (e.g.…”

Section: Discussionmentioning

confidence: 99%

Quasi-periodic oscillations under wavelet microscope: the application of Matching Pursuit algorithm

Lachowicz

Done

2010

A&A

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We zoom in on the internal structure of the low-frequency quasi-periodic oscillation (LF QPO) often observed in black hole binary systems to investigate the physical nature of the lack of coherence in this feature. We show the limitations of standard Fourier power spectral analysis for following the evolution of the QPO with time and instead use wavelet analysis and a new time-frequency technique -Matching Pursuit algorithm -to maximise the resolution with which we can follow the QPO behaviour. We use the LF QPO seen in a very high state of XTE J1550−564 to illustrate these techniques and show that the best description of the QPO is that it is composed of multiple independent oscillations with a distribution of lifetimes but with constant frequency over this duration. This rules out models where there is continual frequency modulation, such as multiple blobs spiralling inwards. Instead it favours models where the QPO is excited by random turbulence in the flow.

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Section: Discussionmentioning

confidence: 99%

Quasi-periodic oscillations under wavelet microscope: the application of Matching Pursuit algorithm

Lachowicz

Done

2010

A&A

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“…Machida et al 2006;Hawley 2009;Romanova et al 2009;Mignone et al 2010, and references therein) have apparently shown that jet formation and acceleration is due to one of two types of physical mechanisms: plasma gun/magnetic towers, as proposed by Contopoulos (1995)/Lynden-Bell (1996, or centrifugal driving, as proposed by Blandford & Payne (1982). What is most important, however, is that these simulations demostrate that at the origin of jet formation and acceleration lies a large-scale magnetic field that threads the central "driving engine" (the central compact object and the surrounding innermost accretion disk).…”

Section: Jet Formation and Destructionmentioning

confidence: 99%

Formation and destruction of jets in X-ray binaries

Kylafis

Contopoulos

Kazanas

et al. 2012

A&A

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Context. Neutron-star and black-hole X-ray binaries (XRBs) exhibit radio jets, whose properties depend on the X-ray spectral state and history of the source. In particular, black-hole XRBs emit compact, steady radio jets when they are in the so-called hard state. These jets become eruptive as the sources move toward the soft state, disappear in the soft state, and then re-appear when the sources return to the hard state. The jets from neutron-star X-ray binaries are typically weaker radio emitters than the black-hole ones at the same X-ray luminosity and in some cases radio emission is detected in the soft state. Aims. Significant phenomenology has been developed to describe the spectral states of neutron-star and black-hole XRBs, and there is general agreement about the type of the accretion disk around the compact object in the various spectral states. We investigate whether the phenomenology describing the X-ray emission on one hand and the jet appearance and disappearance on the other can be put together in a consistent physical picture. Methods. We consider the so-called Poynting-Robertson cosmic battery (PRCB), which has been shown to explain in a natural way the formation of magnetic fields in the disks of AGNs and the ejection of jets. We investigate whether the PRCB can also explain the formation, destruction, and variability of jets in XRBs. Results. We find excellent agreement between the conditions under which the PRCB is efficient (i.e., the type of the accretion disk) and the emission or destruction of the radio jet. Conclusions. The disk-jet connection in XRBs can be explained in a natural way using the PRCB.

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“…Three-dimensional magnetohydrodynamic simulations (Machida et al 2006;Hawley 2009;Romanova et al 2009;Mignone et al 2010) have shown that there are two mechanisms for jet formation, both requiring a strong large-scale magnetic field: plasma gun/magnetic tower (Contopoulos 1995;LyndenBell 1996), and centrifugal driving (Blandford & Payne 1982). Such a magnetic field can originate from a large distance and the advecting flow carries it to the inner region and amplifies it (Igumenshchev 2008;Lovelace et al 2009;Tchekhovskoy et al 2011).…”

Section: Quiescent Statementioning

confidence: 99%

Accretion and ejection in black-hole X-ray transients

Kylafis

Belloni

2015

A&A

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Context. A rich phenomenology has been accumulated over the years regarding accretion and ejection in black-hole X-ray transients (BHTs) and it needs an interpretation. Aims. Here we summarize the current observational picture of the outbursts of BHTs, based on the evolution traced in a hardnessluminosity diagram (HLD), and we offer a physical interpretation. Methods. The basic ingredient in our interpretation is the Poynting-Robertson cosmic battery (PRCB), which provides locally the poloidal magnetic field needed for the ejection of the jet. In addition, we make two assumptions, easily justifiable. The first is that the mass-accretion rate to the black hole in a BHT outburst has a generic bell-shaped form, whose characteristic time scale is much longer than the dynamical or the cooling ones. This is guaranteed by the observational fact that all BHTs start their outburst and end it at the quiescent state, i.e., at very low accretion rate, and that state transitions take place over long time scales (hours to days). The second assumption is that at low accretion rates the accretion flow is geometrically thick, ADAF-like, while at high accretion rates it is geometrically thin. Last, but not least, we demonstrate that the previous history of the system is absolutely necessary for the interpretation of the HLD. Results. Both, at the beginning and the end of an outburst, the PRCB establishes a strong poloidal magnetic field in the ADAF-like part of the accretion flow, and this explains naturally why a jet is always present in the right part of the HLD. In the left part of the HLD, the accretion flow is in the form of a thin disk, and such a disk cannot sustain a strong poloidal magnetic filed. Thus, no jet is expected in this part of the HLD. Finally, the counterclockwise traversal of the HLD is explained as follows: all outbursts start from the quiescent state, in which the inner part of the accretion flow is ADAF-like, threaded by a poloidal magnetic field. As the accretion rate increases and the source moves to the hard state, the poloidal magnetic field in the ADAF forces the flow to remain ADAF and the source to move upwards in the HLD rather than to turn left. Thus, the history of the system determines the counterclockwise traversal of the HLD. As a result, no BHT is expected to ever traverse the entire HLD curve in the clockwise direction. Conclusions. We offer a physical interpretation of accretion and ejection in BHTs with only one parameter, the mass transfer rate, plus the history of the system.

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Formation of Magnetically Supported Disks during Hard-to-Soft Transitions in Black Hole Accretion Flows

Cited by 91 publications

References 44 publications

Quasi-periodic oscillations under wavelet microscope: the application of Matching Pursuit algorithm

Quasi-periodic oscillations under wavelet microscope: the application of Matching Pursuit algorithm

Formation and destruction of jets in X-ray binaries

Accretion and ejection in black-hole X-ray transients

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