Open AccessINTEGRAL/RXTE high‐energy observation of a state transition of GX 339–4
Author(s) -
Belloni T.,
Parolin I.,
Del Santo M.,
Homan J.,
Casella P.,
Fender R. P.,
Lewin W. H. G.,
Méndez M.,
Miller J. M.,
Van Der Klis M.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.09999.x
Subject(s) - physics , spectral line , transition radiation , astrophysics , static timing analysis , energy (signal processing) , satellite , atomic physics , optics , astronomy , radiation , quantum mechanics , computer science , embedded system
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.