NuSTAR DISCOVERY OF AN UNUSUALLY STEADY LONG-TERM SPIN-UP OF THE Be BINARY 2RXP J130159.6-635806
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 ob...
Main Authors: | , , , , , , , , , , , , , , , , |
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Other Authors: | , |
Format: | Article |
Language: | English |
Published: |
IOP Publishing,
2015-11-13T15:05:59Z.
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Subjects: | |
Online Access: | Get fulltext |
Summary: | 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[subscript 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. |
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