Suzaku observation of IGR J16318-4848

¹ Dr. Karl Remeis-Sternwarte and Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwartstraße 7, 96049 Bamberg, Germany e-mail: laura.barragan@sternwarte.uni-erlangen.de
² CRESST, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
³ NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771, USA
⁴ MIT Kavli Institute for Astrophysics and Space Research, 77, Massachusetts Avenue, 37-241, Cambridge, MA 02139, USA
⁵ INTEGRAL Science Data Centre, Geneva Observatory, University of Geneva, Chemin d'Écogia 16, 1290 Versoix, Switzerland
⁶ Space Sciences Laboratory, University of California Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, USA

Received: 15 August 2008
Accepted: 19 October 2009

Abstract

We report on the first Suzaku observation of IGR J16318-4848, the most extreme example of a new group of highly absorbed X-ray binaries that have recently been discovered by the International Gamma-Ray Astrophysics Laboratory (INTEGRAL). The Suzaku observation was carried out between 2006 August 14 and 17, with a net exposure time of 97 ks.
The average X-ray spectrum of the source can be well described () with a continuum model typical for neutron stars i.e., a strongly absorbed power law continuum with a photon index of 0.676(42) and an exponential cutoff at 20.5(6) keV. The absorbing column is . Consistent with earlier work, strong fluorescent emission lines of Fe , Fe , and Ni are observed. Despite the large , no Compton shoulder is seen in the lines, arguing for a non-spherical and inhomogeneous absorber.
Seen at an average 5–60 keV absorbed flux of , the source exhibits significant variability on timescales of hours.