The nature of the X-ray binary IGR J19294+1816 from INTEGRAL, RXTE, and Swift observationsJ. Rodriguez1, J. A. Tomsick2, A. Bodaghee2, J.-A. Zurita Heras1, S. Chaty1, A. Paizis3, and S. Corbel1
1 Laboratoire AIM, CEA/DSM – CNRS – Université Paris Diderot (UMR 7158), CEA Saclay, DSM/IRFU/SAp, 91191 Gif-sur-Yvette, France
2 Space Science Laboratory, 7 Gauss Way, University of California, Berkeley, C1 94720-7450, USA
3 INAF-IASF, Sezione di Milano, via Bassini 15, 20133 Milano, Italy
Received 22 June 2009 / Accepted 9 October 2009
We report the results of a high-energy multi-instrumental campaign with INTEGRAL, RXTE, and Swift of the recently discovered INTEGRAL source IGR J19294+1816. The Swift/XRT data allow us to refine the position of the source to RAJ2000 = 19h 29m 55.9s DecJ2000 = +18° 1838.4 (3.5), which in turn permits us to identify a candidate infrared counterpart. The Swift and RXTE spectra are well fitted with absorbed power laws with hard ( ~ 1) photon indices. During the longest Swift observation, we obtained evidence of absorption in true excess to the Galactic value, which may indicate some intrinsic absorption in this source. We detected a strong (P = 40%) pulsation at 12.43781 (0.00003) s that we interpret as the spin period of a pulsar. All these results, coupled with the possible 117 day orbital period, point to IGR J19294+1816 being an HMXB with a Be companion star. However, while the long-term INTEGRAL/IBIS/ISGRI 18-40 keV light curve shows that the source spends most of its time in an undetectable state, we detect occurrences of short (~ 2000-3000 s) and intense flares that are more typical of supergiant fast X-ray transients. We therefore cannot make firm conclusions on the type of system, and we discuss the possible implications of IGR J19294+1816 being an SFXT.
Key words: X-rays: binaries -- accretion, accretion disks -- stars: individual: IGR J19294+1816 -- stars: individual: IGR J11215-5952 -- stars: individual: IGR J18483-0311
© ESO 2009