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Issue A&A
Volume 450, Number 1, April IV 2006
Page(s) L9 - L12
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20064940

A&A 450, L9-L12 (2006)
DOI: 10.1051/0004-6361:20064940

Letter

IGR J11215-5952: a hard X-ray transient displaying recurrent outbursts

L. Sidoli, A. Paizis and S. Mereghetti

INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, 20133 Milano, Italy
    e-mail: sidoli@iasf-milano.inaf.it

(Received 31 January 2006 / Accepted 2 March 2006)

Abstract
Context.The hard X-ray source IGR J11215-5952 has been discovered with INTEGRAL during a short outburst in 2005 and proposed as a new member of the class of supergiant fast X-ray transients.
Aims.We analysed INTEGRAL public observations of the source field in order to search for previous outbursts from this transient, not reported in literature.
Methods.Our results are based on a systematic re-analysis of INTEGRAL archival observations, using the latest analysis software and instrument calibrations.
Results.We report the discovery of two previously unnoticed outbursts, spaced by intervals of ~330 days, that occurred in July 2003 and May 2004. The 5-100 keV spectrum of IGR J11215-5952 is well described by a cut-off power law, with a photon index of ~0.5, and a cut-off energy ~15-20 keV, typical of High Mass X-ray Binaries hosting a neutron star. A 5-100 keV luminosity of ${\sim}3\times10^{36}$ erg s-1 has been derived (assuming 6.2 kpc, the distance of the likely optical counterpart).
Conclusions.The 5-100 keV spectral properties, the recurrent nature of the outbursts, together with the reduced error region containing the blue supergiant star HD 306414, support the hypothesis that IGR J11215-5952 is a member of the class of the Supergiant Fast X-ray Transients.


Key words: X-rays: stars -- X-rays: individuals: IGR J11215-5952

SIMBAD Objects




© ESO 2006


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