Broadband X-Ray Spectrum of KS 1947+300 with BeppoSAX

• Published in: The Astrophysical journal 2006-08, Vol.647 (2), p.1293-1299
• Main Authors: Naik, S, Callanan, P. J, Paul, B, Dotani, T
• Format: Article
• Language: English
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/505555

We present results obtained from three BeppoSAX observations of the accretion-powered transient X-ray pulsar KS 1947+300 carried out during the declining phase of its 2000 November-2001 June outburst. A detailed spectral study of KS 1947+300 across a wide X-ray band (0.1-100.0 keV) is attempted for the first time here. Timing analysis of the data clearly shows a 18.7 s pulsation in the X-ray light curves in the above energy band. The pulse profile of KS 1947+300 is characterized by a broad peak with sharp rise, followed by a narrow dip. The dip in the pulse profile shows a very strong energy dependence. Broadband pulse phase-averaged spectroscopy obtained with three of the BeppoSAX instruments shows that the energy spectrum in the 0.1-100 keV energy band has three components, a Comptonized component, a 60.6keV blackbody component, and a narrow, weak iron emission line at 6.7 keV with a low column density of material in the line of sight. We place an upper limit of 613 eV on the equivalent width of the iron Ka line at 6.4 keV (for a width of 100 eV). Assuming a spherical blackbody emitting region and the distance of the source to be 10 kpc, the radius of the emitting region is found to be in the range 14-22 km, which rules out the inner accretion disk as the soft X-ray-emitting region.