CaltechAUTHORS
Published December 10, 2015 | Version Submitted + Published
Journal Article Open

The Transient Accereting X-Ray Pulsar XTE J1946+274: Stability of the X-Ray Properties at Low Flux and Updated Orbital Solution

Creators

  • 1. ROR icon University of Maryland, Baltimore County
  • 2. ROR icon University of Erlangen-Nuremberg
  • 3. ROR icon University of Paris
  • 4. ROR icon National Space Science and Technology Center
  • 5. ROR icon University of Alabama in Huntsville
  • 6. ROR icon Marshall Space Flight Center
  • 7. ROR icon California Institute of Technology
  • 8. ROR icon Massachusetts Institute of Technology
  • 9. ROR icon University of California, San Diego
  • 10. ROR icon University of Tübingen
  • 11. ROR icon Saitama University
  • 12. ROR icon Kyoto University
  • 13. ROR icon United States Naval Research Laboratory
  • 14. ROR icon Computational Sciences (United States)

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^(37) erg s^(−1)) and lowest (~5 × 10^(36) erg s^(−1)) observed 3–60 keV luminosities.

Additional Information

© 2015 The American Astronomical Society. Received 2015 August 21; accepted 2015 October 16; published 2015 December 8. D.M.M.-C. and K.P. acknowledge support by Suzaku NASA Guest Observer grant NNX11AD41G and NASA Astrophysical Data Analysis Program grant 12-ADAP12-0118. We acknowledge funding by the Bundesministerium für Wirtschaft und Technologie under Deutsches Zentrum für Luft- und Raumfahrt grants 50OR1113 and 50OR1207 and Deutsche Forschungsgemeinschaft grant WI 1860/11-1. We thank John E. Davis for the development of the SLXfig module, which was used to create Figure 4. M.T.W. and K.S.W. acknowledge support by the Chief of Naval Research and NASA Astrophysical Data Analysis Program grant 12-ADAP12-0118. V.G. acknowledges support by NASA through the Smithsonian Astrophysical Observatory (SAO) contract SV3-73016 to MIT for Support of the Chandra X-Ray Center (CXC) and Science Instruments. CXC is operated by SAO for and on behalf of NASA under contract NAS8-03060. Facilities: Suzaku - Suzaku (ASTRO-EII), Fermi - Fermi Gamma-Ray Space Telescope (formerly GLAST), RXTE - Rossi X-ray Timing Explorer, Swift - Swift Gamma-Ray Burst Mission, INTEGRAL - International Gamma-Ray Astrophysics Laboratory satellite.

Attached Files

Published - Marcu-Cheatham_2015.pdf

Submitted - 1510.05032v1.pdf

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Additional details

Identifiers

Eprint ID
63721
Resolver ID
CaltechAUTHORS:20160115-141426188

Related works

Describes
http://arxiv.org/abs/1510.05032 (URL)

Funding

NASA
NNX11AD41G
NASA
12-ADAP12-0118
Deutsches Zentrum für Luft- und Raumfahrt (DLR)
50OR1113
Deutsches Zentrum für Luft- und Raumfahrt (DLR)
50OR1207
Deutsche Forschungsgemeinschaft (DFG)
WI 1860/11-1
NASA
12-ADAP12- 0118
Smithsonian Astrophysical Observatory
SV3- 73016
NASA
NAS8-03060
Bundesministerium für Wirtschaft und Technologie (BMWi)

Dates

Created
2016-01-15
Created from EPrint's datestamp field
Updated
2021-11-10
Created from EPrint's last_modified field