SUZAKU OBSERVATIONS OF FOUR HEAVILY ABSORBED HMXBs

We report on Suzaku observations of four unidentified sources from the International Gamma-Ray Astrophysics Laboratory ( INTEGRAL) and Swift-Burst Array Telescope Galactic plane surveys. All the sources have a large neutral hydrogen column density and show properties consistent with being supergiant X-ray binaries or supergiant fast X-ray transients (SFXTs), adding to the growing list of heavily absorbed XBs discovered by INTEGRAL. Two of the sources in our sample are approximately constant flux sources, one source shows periodic variation and one source exhibits a short, bright X-ray outburst. The periodicity is transient, suggesting it is produced by a neutron star in an elliptical orbit passing through a stellar wind, possibly one which is significantly clumpy. We analyze the flaring source in several segments to look for spectral variation and discuss the implications of the findings for the nature of the source. We conclude that all four sources in our sample can be identified as highly absorbed high mass X-ray binaries. This confirms the previous identification of IGR16195-4945 and IGR16465-4507 as such and reports new identifications in the cases of IGR16493-4348 and SWJ2000.6+3210. We report SWJ2000.6+3210 as a newly identified transient X-ray pulsar and confirm previous reports of SFXT flaring behavior in IGR16195-4945.