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NuSTAR Discovery of a Cyclotron Line in the Be/X-Ray Binary RX J0520.5–6932 during Outburst

Tendulkar, Shriharsh P. and Fürst, Felix and Pottschmidt, Katja and Bachetti, Matteo and Bhalerao, Varun B. and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Hailey, Charles J. and Harrison, Fiona A. and Stern, Daniel and Tomsick, John A. and Walton, Dominic J. and Zhang, William (2014) NuSTAR Discovery of a Cyclotron Line in the Be/X-Ray Binary RX J0520.5–6932 during Outburst. Astrophysical Journal, 795 (2). Art. No. 154. ISSN 0004-637X.

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We present spectral and timing analysis of NuSTAR observations of RX J0520.5–6932 in the 3-79 keV band collected during its outburst in 2014 January. The target was observed on two epochs and we report the detection of a cyclotron resonant scattering feature with central energies of E_(CRSF) = 31.3_(-0.7)^(+0.8) keV and 31.5_(-0.6)^(+0.7) keV during the two observations, respectively, corresponding to a magnetic field of B ≈ 2 × 10^(12) G. The 3-79 keV luminosity of the system during the two epochs, assuming a nominal distance of 50 kpc, was 3.667 ± 0.007 × 10^(38) erg s^(–1) and 3.983 ± 0.007 × 10^(38) erg s^(–1). Both values are much higher than the critical luminosity of ≈1.5 × 10^(37) erg s^(–1), above which a radiation-dominated shock front may be expected. This adds a new object to the sparse set of three systems that have a cyclotron line observed at luminosities in excess of 10^(38) erg s^(–1). A broad (σ ≈ 0.45 keV) Fe emission line is observed in the spectrum at a central energy of 6.58_(-0.05)^(+0.05) keV in both epochs. The pulse profile of the pulsar was observed to be highly asymmetric with a sharply rising and slowly falling profile of the primary peak. We also observed minor variations in the cyclotron line energy and width as a function of the rotation phase.

Item Type:Article
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URLURL TypeDescription Paper
Bachetti, Matteo0000-0002-4576-9337
Boggs, Steven E.0000-0001-9567-4224
Harrison, Fiona A.0000-0003-2992-8024
Stern, Daniel0000-0003-2686-9241
Additional Information:© 2014 American Astronomical Society. Received 2014 August 3; accepted 2014 September 17; published 2014 October 23. We thank the anonymous referee for detailed suggestions and comments. 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).
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Subject Keywords:accretion, accretion disks; pulsars: general; pulsars: individual (RX J0520.5-6932); stars: neutron; X-rays: binaries; X-rays: bursts; X-rays: stars
Record Number:CaltechAUTHORS:20141202-071735385
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Official Citation:NuSTAR Discovery of a Cyclotron Line in the Be/X-Ray Binary RX J0520.5–6932 during Outburst Shriharsh P. Tendulkar et al. 2014 ApJ 795 154
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52254
Deposited By: Ruth Sustaita
Deposited On:02 Dec 2014 16:39
Last Modified:10 Oct 2017 20:58

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