A study of the low-frequency quasi-periodic oscillations in the X-ray light curves of the black hole candidate XTE J1859+226

Casella, P.; Belloni, T.; Homan, J.; Stella, L.

doi:10.1051/0004-6361:20041231

Cited by 224 publications

(382 citation statements)

References 27 publications

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“…In this context, the smooth continuous transition between the NBOs and the FBOs appears to be very different from the fast, unresolved transitions observed between type-B and type-A QPOs in BHCs (Nespoli et al 2003;Casella et al 2004), i.e. the equivalent of NBOs and FBOs in this analogy.…”

Section: Discussionmentioning

confidence: 69%

A continuous flaring- to normal-branch transition in Scorpius X-1

Casella

Belloni²,

Stella

2006

A&A

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We report the first resolved rapid transition from a Flaring Branch Oscillation to a Normal Branch Oscillation in the RXTE data of the Z source Sco X-1. The transition took place on a time scale of ∼100 s and was clearly associated to the Normal Branch-Flaring Branch vertex in the color-color diagram. We discuss the results in the context of possible association of the Normal Branch Oscillation with other oscillations known both in Neutron-Star and Black-Hole systems, concentrating on the similarities with the narrow 4-6 Hz oscillations observed at high flux in Black-Hole Candidates.

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Section: Discussionmentioning

confidence: 69%

A continuous flaring- to normal-branch transition in Scorpius X-1

Casella

Belloni²,

Stella

2006

A&A

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“…The state is defined by changes in the PDS. The identifying feature is the presence of the so-called type-B QPO, which has been shown not to be an evolution of the one observed in the HIMS (type-C QPO; see Belloni et al 2005;Casella et al 2004Casella et al , 2005Motta et al 2011Motta et al , 2012. Notice that the SIMS in the HRD is characterised by a drop in total fractional rms (the ellipse in Fig.…”

Section: Soft Intermediate Statementioning

confidence: 95%

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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“…These sporadically appearing QPOs in PDS were observed until 2010 May 14. The observed QPOs in hard and hard-intermediate states ) are of the "C" type and in soft-intermediate state are of the "B" type (van der Klis 2004;Casella et al 2005).…”

Section: Introductionmentioning

confidence: 93%

Properties of the propagating shock wave in the accretion flow around GX 339-4 in the 2010 outburst

Debnath

Chakrabarti

Nandi

2010

A&A

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Context. The black hole candidate GX 339-4 exhibited an X-ray outburst in January 2010, which is still continuing. We here discuss the timing and the spectral properties of the outburst using RXTE data. Aims. Our goal is to study the timing and spectral properties of GX 339-4 using its recent outburst data and extract information about the nature of the accretion flow. Methods. We use RXTE archival data of the recent GX 339-4 outburst and analyze them with the NASA HEAsoft package, version 6.8. We then compare the observed quasi-periodic oscillation (QPO) frequencies with those from existing shock oscillation model and obtain the nature of evolution of the shock locations during the outburst. Results. We found that the QPO frequencies are monotonically increasing from 0.102 Hz to 5.69 Hz within a period of ∼26 days. We explain this evolution with the propagating oscillatory shock (POS) solution and find the variation of the initial and final shock locations and strengths. The model fits also give the velocity of the propagating shock wave, which is responsible for the generation of QPOs and their evolutions, at ∼10 m s −1 . We observe from the spectra that up to 2010 April 10, the object was in a hard state. After that, it went to the hard-intermediate state. On April 18, it had a state transition and went to the soft-intermediate state. On May 15, another state transition was observed and the source moved to the soft state. Conclusions. As in the previously fitted outburst sources, this source also showed the tendency of a rapidly increasing QPO frequency (ν QPO ) on a viscous time scale, which can be modeled quite accurately. In this case, the shock seems to have disappeared at about ∼172 Schwarzschild radii, unlike in the 2005 outburst of GRO J1655-40, where the shock disappeared behind the horizon.

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A study of the low-frequency quasi-periodic oscillations in the X-ray light curves of the black hole candidate XTE J1859+226

Cited by 224 publications

References 27 publications

A continuous flaring- to normal-branch transition in Scorpius X-1

A continuous flaring- to normal-branch transition in Scorpius X-1

Accretion and ejection in black-hole X-ray transients

Properties of the propagating shock wave in the accretion flow around GX 339-4 in the 2010 outburst

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