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An XMM-Newton and NuSTAR Study of IGR J18214-1318: A Non-pulsating High-mass X-Ray Binary with a Neutron Star

Fornasini, Francesca M. and Tomsick, John A. and Bachetti, Matteo and Krivonos, Roman A. and Fürst, Felix and Natalucci, Lorenzo and Pottschmidt, Katja and Wilms, Jörn (2017) An XMM-Newton and NuSTAR Study of IGR J18214-1318: A Non-pulsating High-mass X-Ray Binary with a Neutron Star. Astrophysical Journal, 841 (1). Art. No. 35. ISSN 1538-4357. doi:10.3847/1538-4357/aa6ff4.

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IGR J18214-1318, a Galactic source discovered by the International Gamma-Ray Astrophysics Laboratory, is a high-mass X-ray binary (HMXB) with a supergiant O-type stellar donor. We report on the XMM-Newton and NuSTAR observations that were undertaken to determine the nature of the compact object in this system. This source exhibits high levels of aperiodic variability, but no periodic pulsations are detected with a 90% confidence upper limit of 2% fractional rms between 0.00003–88 Hz, a frequency range that includes the typical pulse periods of neutron stars (NSs) in HMXBs (0.1–10^3 s). Although the lack of pulsations prevents us from definitively identifying the compact object in IGR J18214-1318, the presence of an exponential cutoff with e-folding energy ≾30 keV in its 0.3–79 keV spectrum strongly suggests that the compact object is an NS. The X-ray spectrum also shows a Fe Kα emission line and a soft excess, which can be accounted for by either a partial-covering absorber with N_H ≈ 10^(23) cm^(−2), which could be due to the inhomogeneous supergiant wind, or a blackbody component with kT = 1.74_(-0.05)^(+0.04) keV and R_(BB) ≈ 0.3 km, which may originate from NS hot spots. Although neither explanation for the soft excess can be excluded, the former is more consistent with the properties observed in other supergiant HMXBs. We compare IGR J18214-1318 to other HMXBs that lack pulsations or have long pulsation periods beyond the range covered by our observations.

Item Type:Article
Related URLs:
URLURL TypeDescription
Tomsick, John A.0000-0001-5506-9855
Bachetti, Matteo0000-0002-4576-9337
Krivonos, Roman A.0000-0003-2737-5673
Fürst, Felix0000-0003-0388-0560
Natalucci, Lorenzo0000-0002-6601-9543
Pottschmidt, Katja0000-0002-4656-6881
Wilms, Jörn0000-0003-2065-5410
Additional Information:© 2017 American Astronomical Society. Received 2016 August 23. Accepted 2017 April 25. Published 2017 May 22. We thank the anonymous referee for suggestions that improved the clarity and thoroughness of this paper. This work made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). In addition, F.M.F. acknowledges support from the National Science Foundation Graduate Research Fellowship. F.M.F. and J.A.T. acknowledge partial support from NASA under XMM Guest Observer grant NNX15AG31G. R.K. acknowledges support from the Russian Science Foundation (grant 14-12-01315). L.N. wishes to acknowledge financial support by ASI/INAF grant I/037/12/0.
Funding AgencyGrant Number
NSF Graduate Research FellowshipUNSPECIFIED
Russian Science Foundation14-12-01315
Agenzia Spaziale Italiana (ASI)I/037/12/0-011/13
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Subject Keywords:stars: black holes; stars: individual (IGR J18214-1318) ; stars: neutron; X-rays: binaries
Issue or Number:1
Record Number:CaltechAUTHORS:20170522-091006693
Persistent URL:
Official Citation:Francesca M. Fornasini et al 2017 ApJ 841 35
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77622
Deposited By: Ruth Sustaita
Deposited On:22 May 2017 16:45
Last Modified:15 Nov 2021 17:32

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