@InProceedings{SantosStecCastDAmi:2021:StChSp,
               author = "Santos, Jurandi Le{\~a}o and Stecchini, Paulo Eduardo Freires and 
                         Castro, M. and D'Amico, Fl{\'a}vio",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Universidade Estadual 
                         de Campinas (UNICAMP)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)}",
                title = "Study and characterization of the spectral states of 1E 
                         1740.7-2942 in hard X-rays",
                 year = "2021",
         organization = "Simp{\'o}sio Brasileiro de Geof{\'{\i}}sica Espacial e 
                         Aeronomia, 8. (SBGEA)",
             abstract = "The source 1E 1740.7-2942 (1E), located near the Galactic Center, 
                         is an Xray binary whose compact object is classified as a black 
                         hole candidate due to its spectral similarities to Cygnus X-1. The 
                         hard X-ray spectra of 1E (20 < E < 200keV ) can be understood by 
                         the sombrero model, in which thermal photons from the accretion 
                         disk are comptonized in a hot electron corona. In this model, the 
                         X-ray spectra are well adjusted by a power-law, whose index, 
                         Gamma, is used to characterize the sources spectral state. Values 
                         in the literature for this index, however, are quoted over a wide 
                         range (e.g., between 1.2 and 2.5). In this work, we analyzed the 
                         public database of 1E from ISGRI telescope on-board the INTEGRAL 
                         satellite. Data were reduced to obtain spectra in the 20-200 keV 
                         range, as well as light curves in six different bands. We use the 
                         XSPEC environment to perform spectral analysis. Both these tasks 
                         (reduction and spectral analysis) were automated. The data allowed 
                         us to verify that 1E is mostly in the hard (canonical) state and 
                         is one of the most brilliant sources in the region where it is 
                         observed, corroborating previous results. We present a Gamma 
                         indexes distribution, which allow us to distinguish four spectral 
                         states for 1E in hard X-rays. In addition, it was possible to 
                         recover the degeneracy between kT and tau and, also, the 
                         correlation between the parameters E cut and kT. Another 
                         fundamental result was to conclude that, in 1E, the hot electron 
                         corona is most likely static and, therefore, the spectral states 
                         of the source are the consequence of the truncation of the disk 
                         radius, as canonically described by the sombrero model.",
  conference-location = "Online",
      conference-year = "22-26 mar.",
             language = "en",
        urlaccessdate = "09 maio 2024"
}