* Astronomy

Title: The orbital period in the supergiant fast X-ray transient IGR J16465--4507
Authors: D. J. Clark (1,2), V. Sguera (3,4), A.J Bird (1), V. A. McBride (1), A. B. Hill (5), S. Scaringi (6), S. Drave (1), A. Bazzano (4), A.J Dean (1) ((1) University of Southampton, UK, (2) CESR, France, (3) INAF, Bologna, Italy, (4) INAF, Rome, Italy, (5) Laboratoire d'Astrophysique de Grenoble, France, (6) Radboud University Nijmegen, The Netherlands)

Timing analysis of the INTEGRAL-IBIS and Swift-BAT light curves of the Supergiant Fast X-ray Transient (SFXT) IGR J16465-4507 has identified a period of 30.32±0.02 days which we interpret as the orbital period of the binary system. In addition 11 outbursts (9 of which are previously unpublished) have been found between MJD 52652 to MJD 54764, all of which occur close to the region of the orbit we regard as periastron. From the reported flux outbursts, we found a dynamical range in the interval ~30-80. Although in this regard IGR J16465-4507 cannot be considered a classical SFXT for which typical dinamical ranges are >100, still our reported values are significantly greater than that of classical persistent variable supergiant HMXBs (<20), supporting the idea that IGRJ16465-4507 is an intermediate SFXT system, much like few other similar cases reported in the literature.

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