Accretion and ejection in black-hole X-ray transients

Kylafis, N. D.; Belloni, T.

doi:10.1051/0004-6361/201425106

Cited by 41 publications

(48 citation statements)

References 94 publications

(160 reference statements)

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“…In closing, we stress that the correlations between spectral (photon index, cutoff energy) and timing (time lag, rms variability, QPOs) parameters in BHBs imply that they are coupled and strongly suggest that these components appear to have a common underlying origin. The hysteresis of the HID adds another constraint (Kylafis & Belloni 2015). So far, only Comptonization in an extended jet has been able to survive all these tests.…”

Section: Comptonization In the Jet: A Model That Cannot Be Ignoredmentioning

confidence: 98%

Inclination effects on the X-ray emission of Galactic black-hole binaries

Reig

Kylafis

2019

A&A

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Context. Galactic black-hole X-ray binaries (BHBs) emit a compact, optically thick, mildly relativistic radio jet when they are in the hard and hard-intermediate states. In these states, BHBs exhibit a correlation between the time lag of hard photons with respect to softer ones and the photon index of the power law component that characterizes the X-ray spectral continuum above ∼ 10 keV. The correlation, however, shows large scatter. In recent years, several works have brought to light the importance of taking into account the inclination of the systems to understand the X-ray and radio phenomenology of black-hole binaries. Aims. Our objective is to investigate the role that the inclination plays on the correlation between the time lag and the photon index. Methods. We have obtained RXTE energy spectra and light curves of a sample of black-hole binaries with different inclination angles. We have computed the photon index and the time lag between hard and soft photons and have performed a correlation and linear regression analysis of the two variables. We have also computed energy spectra and light curves of black-hole binaries using the Monte Carlo technique that reproduces the process of Comptonization in the jet. We account for the inclination effects by recording the photons that escape from the jet at different angles. From the simulated light curves and spectra we have obtained model-dependent photon index and time lags that we have compared with those obtained from the real data. Results. We find that the correlation between the time lag and the photon index is tight in low-inclination systems and becomes weaker in high-inclination systems. The amplitude of the lags is also larger at low and intermediate inclination angles than at high inclination. We also find that the photon index and the time lag, obtained from the simulated spectra and light curves, also follow different relationships for different inclination angle ranges. Our jet model reproduces the observations remarkably well. The same set of models that reproduces the correlation for the low-inclination systems, also accounts for the correlation for intermediate-and high-inclination systems fairly well. Conclusions. The large dispersion observed in the time lag -photon index correlation in BHBs can naturally be explained as an inclination effect. Comptonization in the jet explains the steeper dependence of the lags on the photon index in low/intermediateinclination systems than in high-inclination ones.

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Section: Comptonization In the Jet: A Model That Cannot Be Ignoredmentioning

confidence: 98%

Inclination effects on the X-ray emission of Galactic black-hole binaries

Reig

Kylafis

2019

A&A

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“…The accretion flow around the black hole consists of an inner hot flow and an outer geometrically thin accretion disk (Esin et al 1997;Kylafis & Belloni 2015). The jet is fed by the hot inner flow, while the thin accretion disk is the source of blackbody photons at the base of the jet.…”

Section: Jet Modelmentioning

confidence: 99%

Correlation of time lag and photon index in GX 339-4

Kylafis

Reig

2018

A&A

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Context. Black hole transients, as a class, exhibit during their outbursts a correlation between the time lag of hard photons with respect to softer ones and the photon index of the hard X-ray power law. The correlation is not very tight and therefore it is necessary to examine it source by source. Aims. The objective of the present work is to investigate in detail the correlation between the time lag and the photon index in GX 339-4, which is the best studied black hole transient. Methods. We have obtained RXTE energy spectra and light curves and have computed the photon index and the time lag of the 9-15 keV photons with respect to the 2-6 keV photons. The observations cover the first stages of the hard state, the pure hard state, and the hard-intermediate state.Results. We have found a tight correlation between time lag and photon index Γ in the hard and hard-intermediate states. At low Γ, the correlation is positive; it becomes negative at high Γ. By assuming that the hard X-ray power-law index Γ is produced by inverse Compton scattering of soft disk photons in the jet, we have reproduced the entire correlation by varying two parameters in the jet: the radius of the jet at its base R 0 and the Thomson optical depth along the jet τ . We have found that as the luminosity of the source increases, R 0 initially increases and then decreases. This behavior is expected in the context of the Cosmic Battery. Conclusions. Our jet model nicely explains the correlation with reasonable values of the parameters R 0 and τ . These parameters also correlate between themselves. As a further test of our model, we predict the break frequency in the radio spectrum as a function of the photon index during the rising part of an outburst.

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“…This association can be related to the production, transport and dissipation of magnetic fields in the inner disc. The presence of hard X-rays emission indicates the presence of a geometrically-thick corona, which makes it easier to produce (Begelman & Armitage 2014;Kylafis & Belloni 2015) and transport (Beckwith, Hawley & Krolik 2009) magnetic flux. Similarly, with the compact jets, the presence of some form of hot, vertically-extended accretion flow may be a necessary condition for an optically-thin radio flares as well.…”

Section: Hard X-ray Flares and Radio Emissionmentioning

confidence: 99%

Wind, jet, hybrid corona and hard X-ray flares: multiwavelength evolution of GRO J1655−40 during the 2005 outburst rise

Kalemci¹,

Begelman²,

Maccarone³

et al. 2016

Mon. Not. R. Astron. Soc.

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We have investigated the complex multiwavelength evolution of GRO J1655−40 during the rise of its 2005 outburst. We detected two hard X-ray flares, the first one during the transition from the soft state to the ultra-soft state, and the second one in the ultra-soft state. The first X-ray flare coincided with an optically thin radio flare. We also observed a hint of increased radio emission during the second X-ray flare. To explain the hard flares without invoking a secondary emission component, we fit the entire data set with the eqpair model. This single, hybrid Comptonization model sufficiently fits the data even during the hard X-ray flares if we allow reflection fractions greater than unity. In this case, the hard X-ray flares correspond to a Comptonizing corona dominated by non-thermal electrons. The fits also require absorption features in the soft and ultra-soft state which are likely due to a wind. In this work we show that the wind and the optically thin radio flare co-exist. Finally, we have also investigated the radio to optical spectral energy distribution, tracking the radio spectral evolution through the quenching of the compact jet and rise of the optically thin flare, and interpreted all data using state transition models.

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Accretion and ejection in black-hole X-ray transients

Cited by 41 publications

References 94 publications

Inclination effects on the X-ray emission of Galactic black-hole binaries

Inclination effects on the X-ray emission of Galactic black-hole binaries

Correlation of time lag and photon index in GX 339-4

Wind, jet, hybrid corona and hard X-ray flares: multiwavelength evolution of GRO J1655−40 during the 2005 outburst rise

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