THE TRANSIENT ACCRETING X-RAY PULSAR XTE J1946+274: STABILITY OF X-RAY PROPERTIES AT LOW FLUX AND UPDATED ORBITAL SOLUTION
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Marcu-Cheatham-2015-THE TRANSIENT ACCRET.pdf
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Author(s)
Marcu-Cheatham, Diana M.
Pottschmidt, Katja
Falkner, Sebastian
Caballero, Isabel
Finger, Mark H.
Jenke, Peter J.
Wilson-Hodge, Colleen A.
Grinberg, Victoria
Hemphill, Paul B.
Kreykenbohm, Ingo
Date Issued
December 2015
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Marcu-Cheatham, Diana M., Katja Pottschmidt, Matthias Kuhnel, Sebastian Muller, Sebastian Falkner, Isabel Caballero, Mark H. Finger, et al. “THE TRANSIENT ACCRETING X-RAY PULSAR XTE J1946+274: STABILITY OF X-RAY PROPERTIES AT LOW FLUX AND UPDATED ORBITAL SOLUTION.” The Astrophysical Journal 815, no. 1 (December 8, 2015): 44. © 2015 The American Astronomical Society
Version
Final published version
Abstract
We present a timing and spectral analysis of the X-ray pulsar XTE J1946+274 observed with Suzaku during an outburst decline in 2010 October and compare with previous results. XTE J1946+274 is a transient X-ray binary consisting of a Be-type star and a neutron star with a 15.75 s pulse period in a 172 days orbit with 2–3 outbursts per orbit during phases of activity. We improve the orbital solution using data from multiple instruments. The X-ray spectrum can be described by an absorbed Fermi–Dirac cut-off power-law model along with a narrow Fe Kα line at 6.4 keV and a weak Cyclotron Resonance Scattering Feature (CRSF) at ~35 keV. The Suzaku data are consistent with the previously observed continuum flux versus iron line flux correlation expected from fluorescence emission along the line of sight. However, the observed iron line flux is slightly higher, indicating the possibility of a higher iron abundance or the presence of non-uniform material. We argue that the source most likely has only been observed in the subcritical (non-radiation dominated) state since its pulse profile is stable over all observed luminosities and the energy of the CRSF is approximately the same at the highest (~5 × 10[superscript 37] erg s[superscript −1]) and lowest (~5 × 10[superscript 36] erg s[superscript −1]) observed 3–60 keV luminosities.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.1088/0004-637x/815/1/44
