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Broadband X-Ray Properties of the Gamma-Ray Binary 1FGL J1018.6–5856

An, Hongjun and Bellm, Eric and Bhalerao, Varun and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Fuerst, Felix and Hailey, Charles J. and Harrison, Fiona A. and Kaspi, Victoria M. and Natalucci, Lorenzo and Stern, Daniel and Tomsick, John A. and Zhang, William W. (2015) Broadband X-Ray Properties of the Gamma-Ray Binary 1FGL J1018.6–5856. Astrophysical Journal, 806 (2). Art. No. 166. ISSN 0004-637X. doi:10.1088/0004-637X/806/2/166.

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We report on NuSTAR, XMM-Newton, and Swift observations of the gamma-ray binary 1FGL J1018.6–5856. We measure the orbital period to be 16.544 ± 0.008 days using Swift data spanning 1900 days. The orbital period is different from the 2011 gamma-ray measurement which was used in the previous X-ray study of An et al. using ~400 days of Swift data, but is consistent with a new gamma-ray solution reported in 2014. The light curve folded on the new period is qualitatively similar to that reported previously, having a spike at phase 0 and broad sinusoidal modulation. The X-ray flux enhancement at phase 0 occurs more regularly in time than was previously suggested. A spiky structure at this phase seems to be a persistent feature, although there is some variability. Furthermore, we find that the source flux clearly correlates with the spectral hardness throughout all orbital phases, and that the broadband X-ray spectra measured with NuSTAR, XMM-Newton, and Swift are well fit with an unbroken power-law model. This spectrum suggests that the system may not be accretion-powered.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bellm, Eric0000-0001-8018-5348
Bhalerao, Varun0000-0002-6112-7609
Boggs, Steven E.0000-0001-9567-4224
Christensen, Finn E.0000-0001-5679-1946
Fuerst, Felix0000-0003-0388-0560
Harrison, Fiona A.0000-0003-2992-8024
Kaspi, Victoria M.0000-0001-9345-0307
Natalucci, Lorenzo0000-0002-6601-9543
Stern, Daniel0000-0003-2686-9241
Tomsick, John A.0000-0001-5506-9855
Zhang, William W.0000-0002-1426-9698
Additional Information:© 2015 American Astronomical Society. Received 2015 March 9; accepted 2015 May 7; published 2015 June 17. We thank R. W. Romani for useful discussions. This work was supported under NASA Contract No. NNG08FD60C, and 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). This research has made use of data obtained from the High Energy Astrophysics Science Archive Research Center (HEASARC), provided by NASA's Goddard Space Flight Center. H.A. acknowledges supports provided by the NASA sponsored Fermi Contract NAS5-00147 and by Kavli Institute for Particle Astrophysics and Cosmology (KIPAC). LN wishes to acknowledge the Italian Space Agency (ASI) for financial support by ASI/INAF grant I/037/12/0-011/13.
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Kavli Institute for Particle Astrophysics and CosmologyUNSPECIFIED
Agenzia Spaziale Italiana (ASI)I/037/12/0-011/13
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Subject Keywords:binaries: close; gamma rays: stars; stars: individual (1FGL J1018.6–5856); X-rays: binaries
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2015-55
Issue or Number:2
Record Number:CaltechAUTHORS:20150803-144537922
Persistent URL:
Official Citation:Broadband X-Ray Properties of the Gamma-Ray Binary 1FGL J1018.6–5856 Hongjun An et al. 2015 ApJ 806 166
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59155
Deposited By: Ruth Sustaita
Deposited On:05 Aug 2015 23:26
Last Modified:10 Nov 2021 22:15

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