Spectral states of the X-ray binary IGR J17091--3624 observed by INTEGRAL and RXTE

F. Capitanio; A. Bazzano; P. Ubertini; A. A. Zdziarski; A. J. Bird; G. De Cesare; A. J. Dean; J. B. Stephen; A. Tarana

doi:10.1086/502641

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Spectral states of the X-ray binary IGR J17091--3624 observed by INTEGRAL and RXTE

F. Capitanio·A. Bazzano·P. Ubertini·A. A. Zdziarski·A. J. Bird·G. De Cesare·A. J. Dean·J. B. Stephen·A. Tarana

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Abstract

IGR J17091-3624 was discovered in 2003 April by INTEGRAL/IBIS during its Galactic Centre Deep Exposure programme. The source was initially detectable only in the 40--100 keV range, but after two days was also detected in the 15-40 keV range. Its flux had by then increased to 40 mCrab and 25 mCrab in the 15-40 keV and 40-100 keV bands respectively. RXTE observed the source simultaneously on 2003 April 20, with an effective exposure of 2 ksec. We report here the spectral and temporal evolution of the source, which shows a transition between the hard and soft states. We analyse in detail the RXTE/INTEGRAL Comptonised spectrum of the hard state as well as the JEM-X detection of a blackbody component during the source softening. Even though the source spectral behaviour and time variability show a similarity with the outburst of the black-hole candidate IGR J17464-3213 (= H1743-322), observed by INTEGRAL in 2003, the nature of its compact object (BH vs. NS) remains controversial.

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F. Capitanio, A. Bazzano, P. Ubertini, A. A. Zdziarski, A. J. Bird, G. De Cesare, A. J. Dean, J. B. Stephen, A. Tarana. 2006-01-23. Spectral states of the X-ray binary IGR J17091--3624 observed by INTEGRAL and RXTE. https://doi.org/10.1086/502641

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