Suzaku observations of the 2013 outburst of KS 1947+300

TL;DR

This study analyzes Suzaku observations of the 2013 outburst of the high-mass X-ray binary KS 1947+300, revealing energy-dependent pulse profiles, spectral features, and a spin-up trend, contributing to understanding neutron star accretion behavior.

Contribution

First detailed timing and spectral analysis of KS 1947+300 during its 2013 outburst using Suzaku data, highlighting unique pulse profile evolution and spectral variations.

Findings

Pulse period of ~18.8 seconds with spin-up observed.

Energy-dependent pulse profile evolution from single to double peaks.

Detection of fluorescent iron emission lines.

Abstract

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 cut-off and an additional black body 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 a very similar behavior of the pulse profile, which is strongly energy dependent, with an evolution from a profile with one peak at low energies to a profile with two peaks of different widths towards 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.