Discovery of X-ray pulsations from IGR J16320-4751 = AX J1631.9-4752

Abstract

We report a discovery of strong modulations of the X-ray flux detected from IGR J16320-4751 = AX J1631.9-4752 with a period of P~1300 sec. We reanalyzed the data of an XMM-Newton ToO performed soon after the discovery of the source by INTEGRAL and found the modulation at a period of P=1309+/-40 sec with a high significance. Modulations of the source flux with two possible periods of ~1300 and ~1500 sec were identified in the ASCA archival data. It is very likely that the modulation can be interpreted as X-ray pulsations, favouring a pulsar as the compact object in IGR/AX J16320-4752. Thus for the moment this source became the fourth source from a new class of highly absorbed binary systems for which the pulsations are observed.