Volume 591, July 2016
|Number of page(s)||9|
|Section||Stellar structure and evolution|
|Published online||13 June 2016|
Suzaku observations of the 2013 outburst of KS 1947+300
1 Dr. Karl-Remeis-Sternwarte and Erlangen Centre for Astroparticle Physics, Sternwartstr. 7, 96049 Bamberg, Germany
2 Department of Physics, University of Maryland Baltimore County, Baltimore, MD 21250, USA
3 CRESST and NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771, USA
4 Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA
5 Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 920093-0424, USA
6 Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
7 Science Operations Division, Science Operations Department of ESA, ESAC, 28692 Villanueva de la Cañada, Madrid, Spain
Received: 14 August 2015
Accepted: 1 March 2016
We report on the timing and spectral analysis of two Suzaku observations with different flux levels of the high-mass X-ray binary KS 1947+300 during its 2013 outburst. In agreement with simultaneous NuSTAR observations, the continuum is well described by an absorbed power law with a cutoff and an additional blackbody component. In addition, we find fluorescent emission from neutral, He-like, and even H-like iron. We determine a pulse period of ~18.8 s with the source showing a spin-up between the two observations. Both Suzaku observations show very similar behavior of the pulse profile, which is strongly energy dependent. This profile has an evolution from a profile with one peak at low energies to a profile with two peaks of different widths toward higher energies seen in both the Suzaku and NuSTAR data. Such an evolution to a more complex profile at higher energies is rarely seen in X-ray pulsars, most cases show the opposite behavior. Pulse phase-resolved spectral analysis shows a variation in the absorbing column density, NH, over pulse phase. Spectra taken during the pulse profile minima are intrinsically softer compared to the pulse phase-averaged spectrum.
Key words: pulsars: individual: KS 1947+300 / X-rays: binaries / accretion, accretion disks
© ESO, 2016
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