INTEGRAL and XMM–Newton observations of the X-ray pulsar IGR J16320−4751/AX J1631.9−4752 |
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| Authors: | J Rodriguez A Bodaghee P Kaaret JA Tomsick E Kuulkers G Malaguti P-O Petrucci C Cabanac M Chernyakova S Corbel S Deluit G Di Cocco K Ebisawa A Goldwurm G Henri F Lebrun A Paizis R Walter L Foschini |
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| Institution: | CEA Saclay, DSM/DAPNIA/Service d'Astrophysique, 91191 Gif sur Yvette, France;Unitémixte de recherche CEA/CNRS/UniversitéParis 7 UMR AIM/7158;ISDC, Chemin d'Ecogia, 16, 1290 Versoix, Switzerland;Observatoire de Genève, Chemin des Maillettes 51, 1290 Sauverny, Switzerland;Department for Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA;Center for Astrophysics and Space Science, University of California at San Diego, MS 0424, La Jolla, CA 92093 USA;ISOC, ESA/ESAC, Urb. Villafranca del Castillo, PO Box 50727, 28080 Madrid, Spain;INAF/IASF, Via Gobetti 101, 40129 Bologna, Italy;Laboratoire d'Astrophysique de l'Obesrvatoire de Grenoble, BP 53X, 38041 Grenoble, France;Centre d'Etude Spatiale des Rayonnements 9, avenue du Colonel Roche - Boite postale 4346 31028 Toulouse Cedex 4, France;NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771, USA;Unitémixte de recherche APC, 11 place Berthelot 75005 Paris, France;INAF/IASF sezione di Milano, Via Bassini 15, 20133 Milano, Italy |
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| Abstract: | We report on observations of the X-ray pulsar IGR J16320−4751 (also known as AX J1631.9−4752) performed simultaneously with International Gamma-Ray Astrophysics Laboratory ( INTEGRAL ) and XMM–Newton . We refine the source position and identify the most likely infrared counterpart. Our simultaneous coverage allows us to confirm the presence of X-ray pulsations at ∼1300 s, that we detect above 20 keV with INTEGRAL for the first time. The pulse fraction is consistent with being constant with energy, which is compatible with a model of polar accretion by a pulsar. We study the spectral properties of IGR J16320−4751 during two major periods occurring during the simultaneous coverage with both satellites, namely a flare and a non-flare period. We detect the presence of a narrow 6.4 keV iron line in both periods. The presence of such a feature is typical of supergiant wind accretors such as Vela X-1 or GX 301−2. We inspect the spectral variations with respect to the pulse phase during the non-flare period, and show that the pulse is solely due to variations of the X-ray flux emitted by the source and not due to variations of the spectral parameters. Our results are therefore compatible with the source being a pulsar in a High Mass X-ray Binary. We detect a soft excess appearing in the spectra as a blackbody with a temperature of ∼0.07 keV. We discuss the origin of the X-ray emission in IGR J16320−4751: while the hard X-rays are likely the result of Compton emission produced in the close vicinity of the pulsar, based on energy argument we suggest that the soft excess is likely the emission by a collisionally energized cloud in which the compact object is embedded. |
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| Keywords: | stars: neutron pulsars: general stars: individual: IGR J16320-4751 AX J1631 9-4752 X-rays: binaries |
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