IGR J16393-4643: A new heavily-obscured X-ray pulsar

Abstract

An analysis of the high-energy emission from IGR J16393-4643 is presented using data from INTEGRAL and XMM-Newton. The source is persistent in the 20-40 keV band at an average flux of 5.1 × 10-11 ergs cm-2 s-1, with variations in intensity by at least an order of magnitude. A pulse period of 912±3 s was discovered in the ISGRI and EPIC light curves. The source spectrum is a strongly-absorbed (NH = (2.5±0.2) × 1023 cm-2) power law that features a high-energy cutoff above 15 keV. Two iron emission lines at 6.4 and 7.1 keV, an iron absorption edge ≳7.1 keV, and a soft excess emission of 7 × 10-15 ergs cm-2 s-1 between 0.5-2 keV, are detected in the EPIC spectrum. The shape of the spectrum does not change with the pulse. Its persistence, pulsation, and spectrum place IGR J16393-4643 among the class of heavily-absorbed HMXBs. The improved position from EPIC is R.A. (J2000)- 16h39m05.4s and Dec.=46°42′12″ (4″ uncertainty) which is compatible with that of 2MASS J16390535-4642137. © 2006 International Astronomical Union.