XMM-Newton view of a hard X-ray transient IGR J17497-2821

Abstract

We present spectral and energy-dependent timing characteristics of the hard X-ray transient IGR J17497–2821 based on XMM–Newton observations performed five and nine days after its outburst on 2006 September 17. We find that the source spectra can be well described by a hard ( ∼ 1.50) power law and a weak multicolour disc blackbody with inner disc temperature kTin ∼ 0.2 keV. A broad iron Kα line with FWHM ∼ 27 000 km s−1, consistent with that arising from an accretion disc truncated at large radius, was also detected. The power density spectra of IGR J17497–2821, derived from the high-resolution (30 µs) timing-mode XMM–Newton observations, are characterized by broad-band noise components that are well modelled by three Lorentzians. The shallow power-law slope, low disc luminosity and the shape of the broad-band power density spectrum indicate that the source was in the hard state. The rms variability in the softer energy bands (0.3–2 keV) found to be ∼1.3 times that in 2–5 and 5–10 keV energy bands. We also present the energy-dependent timing analysis of the RXTE/PCA data, where we find that at higher energies, the rms variability increases with energy. Key words: methods: observational – X-rays: binaries – X-rays: individual: IGR J17497– Show more