The First Suzaku Observation of 4U 1538-522
Abstract
We present results from the first Suzaku observation of the high mass X-ray binary 4U 1538-522. The broad-band spectral coverage of Suzaku allows for a detailed spectral analysis, characterizing the cyclotron resonance scattering feature at 22.5+0.2-0.4 keV and the iron Kα line at 6.417 ± 0.006 keV, as well as placing limits on the strengths of the iron Kβ line and the iron K edge. We track the evolution of the spectral parameters both in time and in luminosity, notably finding no significant correlation between cyclotron line energy and luminosity. A dip and spike in the lightcurve is shown to be associated with a factor of ~2 increase in column density along the line of sight, as well as significant variation in the underlying continuum, implying the accretion of a overdense region of a clumpy stellar wind. A phase-resolved analysis is also presented, with most spectral parameters of interest showing significant variation with phase. Notably, the line-of-sight column density drops drops signficantly at pulse maximum, while the cyclotron line energy reaches a maximum. We discuss the implications of these findings in the context of recent work in the area of cyclotron resonance scattering feature formation.
- Publication:
-
American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014
- Bibcode:
- 2014AAS...22315544H