Long-term evolution of cyclotron line energy in an eclipsing pulsar 4U 1538−522.
In: Monthly Notices of the Royal Astronomical Society, Jg. 527 (2024-01-15), Heft 2, S. 3164-3173
Online
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Zugriff:
We present the timing and spectral analysis of the high-mass X-ray binary source 4U 1538−522 using Nuclear Spectroscopic Telescope Array (NuSTAR) observations. One of the observations partially covers the X-ray eclipse of the source along with eclipse ingress. The source is found to spin down at the rate of 0.163 ± 0.002 s yr −1 between ∼54973 and 58603 MJD. It is evident that at time ∼58620 MJD, a torque reversal occurred; thereafter, the source exhibited a spin-up trend at the rate −(0.305 ± 0.018) s yr −1 until 59275 MJD. A recent NuSTAR observation finds the pulse period of the source: (526.2341 ± 0.0041) s. The pulse profile exhibits a transition from double-peaked to single-peaked nature above ∼30 keV. We analysed the overall trend of the temporal evolution of fundamental cyclotron resonance scattering feature, E cyc , incorporating recent NuSTAR measurements. Initially, during the time span ∼50452.16–55270.8 MJD, the cyclotron line energy is found to increase at a rate of 0.11 ± 0.03 keV yr −1 , which is further followed by a decrease at a rate −0.14 ± 0.01 keV yr −1 between 55270.8 and 59267 MJD. The combined measurements in the time span 50452.16–59267 MJD reveal that the cyclotron line energy is increasing linearly at a rate of 0.08 ± 0.02 keV yr −1 . [ABSTRACT FROM AUTHOR]
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Titel: |
Long-term evolution of cyclotron line energy in an eclipsing pulsar 4U 1538−522.
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Autor/in / Beteiligte Person: | Tamang, Ruchi ; Ghising, Manoj ; Tobrej, Mohammed ; Rai, Binay ; Paul, Bikash Chandra |
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Zeitschrift: | Monthly Notices of the Royal Astronomical Society, Jg. 527 (2024-01-15), Heft 2, S. 3164-3173 |
Veröffentlichung: | 2024 |
Medientyp: | academicJournal |
ISSN: | 0035-8711 (print) |
DOI: | 10.1093/mnras/stad2907 |
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