INTEGRAL/RXTE high-energy observation of a state transition of GX 339–4 |
| |
| Authors: | T Belloni I Parolin M Del Santo J Homan P Casella R P Fender W H G Lewin M Méndez J M Miller M van der Klis |
| |
| Institution: | INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (LC), Italy;INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica di Roma, Via Fosso del Cavaliere 100, I-00133 Roma, Italy;Center for Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA;School of Physics and Astronomy, University of Southampton, Southampton, Hampshire, SO17 1BJ;SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, the Netherlands;Center for Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA;Astronomical Institute 'Anton Pannekoek', University of Amsterdam, and Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ, Amsterdam, the Netherlands |
| |
| Abstract: | On 2004 August 15, we observed a fast (shorter than 10 h) state transition in the bright black hole transient GX 339–4 simultaneously with Rossi X-Ray Timing Explorer ( RXTE ) and INTEGRAL . This transition was evident both in timing and spectral properties. Combining the data from the Proportional Counter Array (PCA), the High-Energy X-ray Timing Experiment (HEXTE) and the Imager on Board the INTEGRAL Satellite (IBIS), we obtained good quality broad-band (3–200 keV) energy spectra before and after the transition. These spectra indicate that the hard component steepened. Also, the high-energy cut-off that was present at ～70 keV before the transition was not detected after the transition. This is the first time that an accurate determination of the broad-band spectrum across such a transition has been measured on a short time-scale. It shows that, although some spectral parameters do not change abruptly through the transition, the high-energy cut-off increases/disappears rather fast. These results constitute a benchmark on which to test theoretical models for the production of the hard component in these systems. |
| |
| Keywords: | accretion accretion discs black hole physics X-rays: binaries |
|
|
