* Astronomy

Title: An XMM-Newton Spectral and Timing Study of IGR J16207-5129: An Obscured and Non-Pulsating HMXB
Authors: John A. Tomsick (SSL/UCB), Sylvain Chaty (AIM - Univ. Paris VII and CEA Saclay), Jerome Rodriguez (AIM - Univ. Paris VII and CEA Saclay), Roland Walter (ISDC, Observatoire de Geneve), Philip Kaaret (Univ. of Iowa), Gagik Tovmassian (UNAM, Ensenada)

We report on a 12 hr XMM-Newton observation of the supergiant High-Mass X-ray Binary IGR J16207-5129. This is only the second soft X-ray (0.4-15 keV, in this case) study of the source since it was discovered by the INTEGRAL satellite. The average energy spectrum is very similar to those of neutron star HMXBs, being dominated by a highly absorbed power-law component with a photon index of 1.15. The spectrum also exhibits a soft excess below 2 keV and an iron Kalpha emission line at 6.39±0.03 keV. For the primary power-law component, the column density is 1.19E23 cm^-2, indicating local absorption, likely from the stellar wind, and placing IGR J16207-5129 in the category of obscured IGR HMXBs. The source exhibits a very high level of variability with an rms noise level of 64%±21% in the 0.0001 to 0.05 Hz frequency range. Although the energy spectrum suggests that the system may harbour a neutron star, no pulsations are detected with a 90% confidence upper limit of 2% in a frequency range from 0.0001 to 88 Hz. We discuss similarities between IGR J16207-5129 and other apparently non-pulsating HMXBs, including other IGR HMXBs as well as 4U 2206+54  and 4U 1700-377.

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