2010ApJ...717.1022D


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.16CEST10:25:43

2010ApJ...717.1022D - Astrophys. J., 717, 1022-1036 (2010/July-2)

Variability and spectral modeling of the hard X-ray emission of GX 339-4 in a bright Low/Hard state.

DROULANS R., BELMONT R., MALZAC J. and JOURDAIN E.

Abstract (from CDS):

We study the high-energy emission of the Galactic black hole candidate GX 339-4 using INTEGRAL/SPI and simultaneous RXTE/PCA data. By the end of 2007 January, when it reached its peak luminosity in hard X-rays, the source was in a bright hard state. The SPectrometer on INTEGRAL (SPI) data from this period show a good signal-to-noise ratio, allowing a detailed study of the spectral energy distribution up to several hundred keV. As a main result, we report on the detection of a variable hard spectral feature (≥150 keV) which represents a significant excess with respect to the cutoff power-law shape of the spectrum. The SPI data suggest that the intensity of this feature is positively correlated with the 25-50 keV luminosity of the source and the associated variability timescale is shorter than 7 hr. The simultaneous Proportional Counter Array data, however, show no significant change in the spectral shape, indicating that the source is not undergoing a canonical state transition. We analyzed the broadband spectra in the lights of several physical models, assuming different heating mechanisms and properties of the Comptonizing plasma. For the first time, we performed quantitative model fitting with the new versatile Comptonization code BELM, accounting self-consistently for the presence of a magnetic field. We show that a magnetized medium subject to pure non-thermal electron acceleration provides a framework for a physically consistent interpretation of the observed 4-500 keV emission. Moreover, we find that the spectral variability might be triggered by the variations of only one physical parameter, namely the magnetic field strength. Therefore, it appears that the magnetic field is likely to be a key parameter in the production of the Comptonized hard X-ray emission.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - magnetic fields - methods: observational - radiation mechanisms: general - X-rays: individual: GX 339-4

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 V* V381 Nor HXB 15 50 58.6520652623 -56 28 35.309070422   17.95 16.6     K3III 1062 0
2 IGR J16318-4848 HXB 16 31 48.3102815892 -48 49 00.664215918           ~ 159 0
3 4U 1642-45 LXB 16 45 47.7 -45 36 40     14.30     ~ 388 1
4 [GHJ2008] 3 HXB 16 50 00.980 -49 57 43.60     11.89     K4V 358 0
5 NAME OAO 1657-41 HXB 17 00 48.884 -41 39 21.46           Ofpe/WN9 213 0
6 V* V821 Ara HXB 17 02 49.3810714542 -48 47 23.163091737 16.20 16.30 15.5     ~ 1826 0
7 HD 153919 HXB 17 03 56.7728262865 -37 50 38.912077679 6.06 6.78 6.51 6.08 5.90 O6Iafcp 769 1
8 HD 226868 HXB 19 58 21.6758193269 +35 12 05.782512305 9.38 9.72 8.91 8.42   O9.7Iabpvar 3997 0

    Equat.    Gal    SGal    Ecl

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2021.04.16-10:25:43

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