Sigma hard X-ray observations of GX 339-4 during the hard state and a transition to the soft state

Bouchet, L.; Jourdain, E.; Mandrou, P.; Roques, J. P.; Laurent, P.; Lebrun, F.; Paul, J.; Salotti, L.; Sunyaev, R.; Churazov, E.; Gilfanov, M.; Khavenson, N.; Diachkov, A.; Chulkov, I.; Novikov, B.; Kuznetsov, A.

doi:10.1086/172555

Cited by 14 publications

(11 citation statements)

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“…Source-background rocking of the two clusters provides a direct measurement of the HEXTE background with measured long term systematic uncertainties of < 1% (Rothschild et al 1998). Although no other strong sources in the field around GX 339−4 are known (Covault, Grindlay & Manandhar 1992;Bouchet et al 1993;Trudolyubov et al 1998), we extracted individual background spectra for both HEXTE cluster background positions to check for contamination of the spectrum from weak background sources. In all cases the background spectra differed by ∼ < 1 cps.…”

Section: Rxte Data Extractionmentioning

confidence: 99%

Low‐Luminosity States of the Black Hole Candidate GX 339−4. I.ASCAand Simultaneous Radio/RXTEObservations

Wilms

Nowak

Dove

et al. 1999

ApJ

100

148

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We discuss a series of observations of the black hole candidate GX 339−4 in low luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets and eight separate Rossi X-ray Timing Explorer (RXTE) data sets. Three of the RXTE observations were strictly simultaneous with 843 MHz and 8.3-9.1 GHz radio observations. All of these observations have (3-9 keV) flux < ∼ 10 −9 ergs s −1 cm −2 . The ASCA data show evidence for an ≈ 6.4 keV Fe line with equivalent width ≈ 40 eV, as well as evidence for a soft excess that is well-modeled by a power law plus a multicolor blackbody spectrum with peak temperature ≈ 150-200 eV. The RXTE data sets also show evidence of an Fe line with equivalent widths ≈ 20-140 eV. Reflection models show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. 'Sphere+disk' Comptonization models and Advection Dominated Accretion Flow (ADAF) models also provide reasonable descriptions of the RXTE data. The former models yield coronal temperatures in the range 20-50 keV and optical depths of τ ≈ 3. The model fits to the X-ray data, however, do not simultaneously explain the observed radio properties. The most likely source of the radio flux is synchrotron emission from an extended outflow of size greater than O(10 7 GM/c 2 ). Subject headings: accretion -black hole physics -Stars: binaries -X-rays: Stars A bpl : Power law normalization (photons keV −1 cm −2 s −1 at 1 keV). E l : line energy. A l : Line normalization (photons cm −2 s −1 in the line). EW: line equivalent width. Uncertainties are at the 90% confidence level for one interesting parameter (∆χ 2 = 2.71). FIG. 1.-GX 339−4 ASCA observation of 1994 August 24 with energy bins rebinned by a factor of 25 for clarity. Model and associated residuals (data/model) are for the best fit multicolor blackbody plus broken power law without a Gaussian line component. For clarity, only the SIS0 (circles) and GIS2 (triangles) data are shown.

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Section: Rxte Data Extractionmentioning

confidence: 99%

Low‐Luminosity States of the Black Hole Candidate GX 339−4. I.ASCAand Simultaneous Radio/RXTEObservations

Wilms

Nowak

Dove

et al. 1999

ApJ

100

148

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“…Higher values for Γ were detected in spectra observed up to 200 keV (Γ = 2.0 ± 0.3; Dolan et al 1987) and to 1.3 MeV Send offprint requests to: A. Corongiu, e-mail: corongiu@ca.astro.it (Bouchet et al 1993). Most observations in the low state indicate the presence of the fluorescence Fe line (Ueda et al 1994;Zdziarski et al 1998;Dolan et al 1987), with an equivalent width of about 50−100 eV.…”

Section: Introductionmentioning

confidence: 97%

The X-ray spectrum of the black hole candidate GX339-4 in a low state

Corongiu

Chiappetti

Haardt

et al. 2003

A&A

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Abstract. We report on four observations of the black hole candidate GX 339-4 collected in the spectral range 0.4−140 keV with the BeppoSAX satellite during 1997. All our spectra are typical of a black hole candidate in its low-hard state, i.e. are dominated by the hard tail of the emission from the corona. Although the direct emission from the accretion disk in the soft X-ray range is weak, spectra are well described only with models that take into consideration the Compton reflection of hard X-rays from the corona onto the surface of an accretion disk of non negligible extent.

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“…The best fit values for the model's two free parameters, temperature and optical depth, are almost always in the range 30 -300 keV and 0.1 -5, respectively Bouchet et al 1993;Johnson et al 1993;Zdziarski et al 1994). There is certainly no selection effect that could explain this comparatively narrow range of parameters in the AGN, for most are discovered by optical, ultraviolet, or radio searches.…”

Section: Introductionmentioning

confidence: 97%

The Inverse Compton Thermostat in Hot Plasmas near Accreting Black Holes

Pietrini

Krolik

1995

ApJ

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The X-ray spectra of accreting black hole systems generally contain components (sometimes dominating the total emission) which are well-fit by thermal Comptonization models with temperatures ∼ 100 keV. We demonstrate why, over many orders of magnitude in heating rate and seed photon supply, hot plasmas radiate primarily by inverse Compton scattering, and find equilibrium temperatures within a factor of a few of 100 keV. We also determine quantitatively the (wide) bounds on heating rate and seed photon supply for which this statement is true.Plasmas in thermal balance in this regime obey two simple scaling laws: ΘτT ≃ 0.1(l h /ls) 1/4 ; and α ≃ 1.6(ls/l h ) 1/4 . Here the hot plasma heating rate compactness is l h , the seed photon compactness is ls, the temperature in electron rest mass units is Θ, and the Thomson optical depth is τT . The coefficient in the first expression is weakly-dependent on plasma geometry; the second expression is independent of geometry. Only when ls/l h is a few tenths or greater is there a weak secondary dependence in both relations on τT .Because α is almost independent of everything but ls/l h , the observed power law index may be used to estimate ls/l h . In both AGN and stellar black holes, the mean value estimated this way is ls/l h ∼ 0.1, although there is much greater sample dispersion among stellar black holes than among AGN. This inference favors models in which the intrinsic (as opposed to reprocessed) luminosity in soft photons entering the hot plasma is small, or in which the hard X-ray production is comparatively distant from the source of soft photons. In addition, it predicts that ΘτT ≃ 0.1 -0.2, depending primarily on plasma geometry. It is possible to construct coronal models (i.e. models in which ls/l h ≃ 0.5) which fit the observed spectra, but they are tightly constrained: τT must be ≃ 0.08 and Θ ≃ 0.8.

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Sigma hard X-ray observations of GX 339-4 during the hard state and a transition to the soft state

Cited by 14 publications

References 0 publications

Low‐Luminosity States of the Black Hole Candidate GX 339−4. I.ASCAand Simultaneous Radio/RXTEObservations

Low‐Luminosity States of the Black Hole Candidate GX 339−4. I.ASCAand Simultaneous Radio/RXTEObservations

The X-ray spectrum of the black hole candidate GX339-4 in a low state

The Inverse Compton Thermostat in Hot Plasmas near Accreting Black Holes

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