Gamma‐Ray Spectral States of Galactic Black Hole Candidates

Grove, J. E.; Johnson, W. N.; Kroeger, R. A.; McNaron-Brown, K.; Skibo, J. G.; Phlips, Bernard F.

doi:10.1086/305746

Cited by 222 publications

(297 citation statements)

References 54 publications

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“…Soft γ-ray spectra similar in shape to that of Cyg X-1 have been observed from other black-hole binaries in the hard state (e.g. Grove et al 1998;Grebenev, Sunyaev & Pavlinsky 1997).…”

Section: Comparison With Black-hole and Neutron-star Sourcessupporting

confidence: 63%

Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications

Zdziarski¹,

Poutanen²,

Mikołajewska³

et al. 1998

Monthly Notices of the Royal Astronomical Society

197

217

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We present X-ray/γ-ray spectra of the binary GX 339-4 observed in the hard state simultaneously by Ginga and CGRO OSSE during an outburst in 1991 September. The Ginga X-ray spectra are well represented by a power law with a photon spectral index of Γ ≃ 1.75 and a Compton reflection component with a fluorescent Fe Kα line corresponding to a solid angle of an optically-thick, ionized, medium of ∼ 0.4×2π. The OSSE data ( 50 keV) require a sharp high-energy cutoff in the power-law spectrum. The broad-band spectra are very well modelled by repeated Compton scattering in a thermal plasma with an optical depth of τ ∼ 1 and kT ≃ 50 keV. We also study the distance to the system and find it to be > ∼ 3 kpc, ruling out earlier determinations of ∼ 1 kpc. Using this limit, the observed reddening and the orbital period, we find the allowed range of the mass of the primary is consistent with it being a black hole.We find the data are incosistent with models of either homogenous or patchy coronae above the surface of an accretion disc. Rather, they are consistent with the presence of a hot inner hot disc with the viscosity parameter of α ∼ 1 accreting at a rate close to the maximum set by advection. The hot disc is surrounded by a cold outer disc, which gives rise to the reflection component and a soft X-ray excess, also present in the data. The seed photons for Comptonization are unlikely to be due to thermal synchrotron radiation. Rather, they are supplied by the outer cold disc and/or cold clouds within the hot disc. e ± pair production is negligible if electrons are thermal. The hot disc model, which scaled parameters are independent of the blackhole mass, is supported by the similarity of the spectrum of GX 339-4 to those of other black-hole binaries and Seyfert 1s. On the other hand, their spectra in the soft γ-ray regime are significantly harder than those of weakly-magnetized neutron stars. Based on this difference, we propose that the presence of broad-band spectra corresponding to thermal Comptonization with kT > ∼ 50 keV represents a black-hole signature.

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“…Soft γ-ray spectra similar in shape to that of Cyg X-1 have been observed from other black-hole binaries in the hard state (e.g. Grove et al 1998;Grebenev, Sunyaev & Pavlinsky 1997).…”

Section: Comparison With Black-hole and Neutron-star Sourcessupporting

confidence: 63%

Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications

Zdziarski¹,

Poutanen²,

Mikołajewska³

et al. 1998

Monthly Notices of the Royal Astronomical Society

197

217

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“…Indeed, in some of these sources, during their hard states, the X-ray spectrum extends up to several hundreds of keV without any evidence of cutoff (e.g., KS 1731-260 andGX 354-0, Barret &Vedrenne 1994; Aql X-1, Harmon et al 1996). This behaviour at high energies is also similar to that of Black Hole Candidates in the so-called power-law gamma-ray state (Grove et al 1998). The similarity of the observed RB spectrum to that of atoll sources in hard state would be consistent with our classification, discussed in Sect.…”

Section: Discussionsupporting

confidence: 88%

The discovery of hard X-ray emission in the persistent flux of the Rapid Burster

Falanga¹,

Farinelli

Goldoni³

et al. 2004

A&A

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Abstract.We report the first detection with INTEGRAL of persistent hard X-ray emission (20 to 100 keV) from the Rapid Burster (MXB 1730-335), and describe its full spectrum from 3 to 100 keV. The source was detected on February/March 2003 during one of its recurrent outbursts. The source was clearly detected with a high signal to noise ratio during the single pointings and is well distinguished from the neighboring source GX 354-0. The 3-100 keV X-ray spectrum of the persistent emission is well described by a two-component model consisting of a blackbody plus a power-law with photon index ∼2.4. The estimated luminosity was ∼8.5 × 10 36 erg s −1 in the 3-20 keV energy band and ∼1.3 × 10 36 erg s −1 in the 20-100 keV energy range, for a distance of 8 kpc.

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“…Motta et al 2009). The high-energy spectrum is now of non-thermal nature (see also Grove et al 1998). …”

Section: Hard Intermediate 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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Gamma‐Ray Spectral States of Galactic Black Hole Candidates

Cited by 222 publications

References 54 publications

Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications

Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications

The discovery of hard X-ray emission in the persistent flux of the Rapid Burster

Accretion and ejection in black-hole X-ray transients

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