Obscured HMXB unveiled by integral and XMM-Newton

During the first year in operation, INTEGRAL, the European Space Agency's gamma-ray observatory, detected more than 28 new bright sources which emit the bulk of their emission above 10 keV. Follow-up observations of a subset of these sources in the X-ray band with XMM-Newton indicate that 80% of them are very strongly absorbed. More than half of these absorbed sources show pulsations with long periods ranging from 139 to 1300s, i.e., they are slow X-ray pulsars. The infrared counterparts are not strongly absorbed demonstrating that the absorbing matter is local to the sources. Many of these new sources are super-giant high-mass X-ray binaries (EAM) in which the stellar wind of the companion star is accreted onto the compact object. The large local absorption in these new sources can be understood if the compact objects are buried deep in dense stellar winds. These new objects represent half of the population of wind-fed supergiant HMXB.