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

Marcu-Cheatham, Diana M. and Pottschmidt, Katja and Kühnel, Matthias and Müller, Sebastian and Falkner, Sebastian and Caballero, Isabel and Finger, Mark H. and Jenke, Peter J. and Wilson-Hodge, Colleen A. and Fürst, Felix and Grinberg, Victoria and Hemphill, Paul B. and Kreykenbohm, Ingo and Klochkov, Dmitry and Rothschild, Richard E. and Terada, Yukikatsu and Enoto, Teruaki and Iwakiri, Wataru B. and Wolff, Michael T. and Becker, Peter A. and Wood, Kent S. and Wilms, Jörn (2015) The Transient Accereting X-Ray Pulsar XTE J1946+274: Stability of the X-Ray Properties at Low Flux and Updated Orbital Solution. Astrophysical Journal, 815 (1). Art. No. 44. ISSN 0004-637X.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Marcu-Cheatham, Diana M.0000-0001-8061-611X
Pottschmidt, Katja0000-0002-4656-6881
Falkner, Sebastian0000-0001-5209-991X
Wilson-Hodge, Colleen A.0000-0002-8585-0084
Fürst, Felix0000-0003-0388-0560
Grinberg, Victoria0000-0003-2538-0188
Hemphill, Paul B.0000-0002-1676-6954
Kreykenbohm, Ingo0000-0001-7335-1803
Terada, Yukikatsu0000-0002-2359-1857
Enoto, Teruaki0000-0003-1244-3100
Iwakiri, Wataru B.0000-0002-0207-9010
Wolff, Michael T.0000-0002-4013-5650
Wood, Kent S.0000-0002-7376-3151
Wilms, Jörn0000-0003-2065-5410
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.
Funding AgencyGrant Number
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OR1113
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OR1207
Deutsche Forschungsgemeinschaft (DFG)WI 1860/11-1
NASA12-ADAP12- 0118
Smithsonian Astrophysical ObservatorySV3- 73016
Bundesministerium für Wirtschaft und Technologie (BMWi)UNSPECIFIED
Subject Keywords:accretion, accretion disks; pulsars: individual (XTE J1946+274) ; X-rays: binaries
Issue or Number:1
Record Number:CaltechAUTHORS:20160115-141426188
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Official Citation:Diana M. Marcu-Cheatham et al 2015 ApJ 815 44
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63721
Deposited By: Ruth Sustaita
Deposited On:15 Jan 2016 23:40
Last Modified:28 Jan 2021 23:10

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