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Published August 20, 2015 | Version Submitted + Published
Journal Article Open

NuSTAR discovery of an unusually steady long-term spin-up of the Be binary 2RXP J130159.6-635806

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Abstract

We present spectral and timing analyses of Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the accreting X-ray pulsar 2RXP J130159.6–635806. The source was serendipitously observed during a campaign focused on the gamma-ray binary PSR B1259–63 and was later targeted for a dedicated observation. The spectrum has a typical shape for accreting X-ray pulsars, consisting of a simple power law with an exponential cutoff starting at ~7 keV with a folding energy of E_(fold) ≃ 18 keV. There is also an indication of the presence of a 6.4 keV iron line in the spectrum at the ~3σ significance level. NuSTAR measurements of the pulsation period reveal that the pulsar has undergone a strong and steady spin-up for the last 20 years. The pulsed fraction is estimated to be ~80%, and is constant with energy up to 40 keV. The power density spectrum shows a break toward higher frequencies relative to the current spin period. This, together with steady persistent luminosity, points to a long-term mass accretion rate high enough to bring the pulsar out of spin equilibrium.

Additional Information

© 2015 The American Astronomical Society. Received 2015 May 27; accepted 2015 July 16; published 2015 August 18. This research has made use of data obtained with NuSTAR, a project led by Caltech, funded by NASA and managed by NASA/JPL, and has utilized the NUSTARDAS software package, jointly developed by the ASDC (Italy) and Caltech (USA). This research has also made use of data obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States. A.L. and S.T. acknowledge support from Russian Science Foundation (grant 14-12-01287). Facilities: NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, XMM-Newton - Newton X-Ray Multimirror Mission satellite.

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Published - Krivonos_2015.pdf

Submitted - 1507.04534v1.pdf

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1507.04534v1.pdf

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Additional details

Identifiers

Eprint ID
59133
Resolver ID
CaltechAUTHORS:20150801-084010223

Related works

Describes
http://arxiv.org/abs/1507.04534 (URL)

Funding

NASA/JPL/Caltech
European Space Agency (ESA)
Russian Science Foundation
14-12-01287

Dates

Created
2015-08-06
Created from EPrint's datestamp field
Updated
2021-11-10
Created from EPrint's last_modified field

Caltech Custom Metadata

Caltech groups
NuSTAR, Space Radiation Laboratory
Other Numbering System Name
Space Radiation Laboratory
Other Numbering System Identifier
2015-41