2006/11/02 by A. Joinet, E. Jourdain, J. Malzac +4 · 2 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Binary number #Electron #Electron temperature #Energy (signal processing) #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Optical depth #Plasma #Reflection (computer programming) #Spectral line #Thermal #astro-ph
paper · pdf · doi:10.1086/510326
published as Astrophys.J.657:400-408,2007 · 12 pages, 6 figures, accepted for publication in ApJ
arxiv created 2006/11/02 · openalex publication_date 2007/03/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We present the analysis of the high-energy emission of the Galactic black hole binary GX 339-4 in a low/hard state at the beginning of its 2004 outburst. The data from 273 ks of INTEGRAL observations, spread over 4 weeks, are analyzed, along with the existing simultaneous RXTE HEXTE and PCA data. During this period, the flux increases by a factor of ≃3, while the spectral shape is quite unchanged, at least up to 150 keV. The high-energy data allow us to detect the presence of a high-energy cutoff, generally related to thermal mechanisms, and to estimate the plasma parameters in the framework of the Comptonization models. We found an electron temperature of 60-70 keV and an optical depth of around 2.5, with a rather low reflection factor (0.2-0.4). In the last observation, we detected a high-energy excess above 200 keV with respect to thermal Comptonization, while at lower energies the spectrum is practically identical to the previous one taken just 2 days before. This suggests that the low- and high-energy components have a different origin.