A Possible Phase-dependent Absorption Feature in the Transient X-Ray Pulsar SAX J2103.5+4545

Journal article

Publication Details

Author(s): Brumback MC, Hickox RC, Furst FS, Pottschmidt K, Hemphill P, Tomsick JA, Wilms J, Ballhausen R
Journal: Astrophysical Journal
Publication year: 2018
Volume: 852
Journal issue: 2
ISSN: 0004-637X
eISSN: 1538-4357


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 similar to 12 keV might, with further study, be classified as a cyclotron line, does show strong pulse-phase dependence.

FAU Authors / FAU Editors

Ballhausen, Ralf
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik

External institutions with authors

Dartmouth College
European Space Astronomy Centre (ESAC)
Massachusetts Institute of Technology (MIT)
University of California, Berkeley
University of Maryland, Baltimore County

How to cite

Brumback, M.C., Hickox, R.C., Furst, F.S., Pottschmidt, K., Hemphill, P., Tomsick, J.A.,... Ballhausen, R. (2018). A Possible Phase-dependent Absorption Feature in the Transient X-Ray Pulsar SAX J2103.5+4545. Astrophysical Journal, 852(2). https://dx.doi.org/10.3847/1538-4357/aa9e91

Brumback, M. C., et al. "A Possible Phase-dependent Absorption Feature in the Transient X-Ray Pulsar SAX J2103.5+4545." Astrophysical Journal 852.2 (2018).


Last updated on 2019-23-08 at 08:32