2018ApJ...852..132B -
Astrophys. J., 852, 132-132 (2018/January-2)
A possible phase-dependent absorption feature in the transient X-ray pulsar SAX J2103.5+4545.
BRUMBACK M.C., HICKOX R.C., FURST F.S., POTTSCHMIDT K., HEMPHILL P., TOMSICK J.A., WILMS J. and BALLHAUSEN R.
Abstract (from CDS):
We present an X-ray spectral and timing analysis of two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the transient Be X-ray binary SAX J2103.5+4545 during its 2016 April outburst, which was characterized by the highest flux since NuSTAR's launch. These observations provide detailed hard X-ray spectra of this source during its bright precursor flare and subsequent fainter regular outburst for the first time. In this work, we model the phase-averaged spectra for these observations with a negative and positive power law with an exponential cutoff (NPEX) model and compare the pulse profiles at different flux states. We found that the broadband pulse profile changes from a three-peaked pulse in the first observation to a two-peaked pulse in the second observation, and that each of the pulse peaks has some energy dependence. We also perform pulse-phase spectroscopy and fit phase-resolved spectra with NPEX to evaluate how spectral parameters change with pulse phase. We find that while the continuum parameters are mostly constant with pulse phase, a weak absorption feature at ∼12 keV might, with further study, be classified as a cyclotron line, does show strong pulse-phase dependence.
Abstract Copyright:
© 2018. The American Astronomical Society. All rights reserved.
Journal keyword(s):
pulsars: individual: SAX J2103.5+4545 - stars: neutron - X-rays: binaries - X-rays: binaries
Simbad objects:
4
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