Continued decay in the cyclotron line energy in Hercules X-1

@article{Staubert2016ContinuedDI,
  title={Continued decay in the cyclotron line energy in Hercules X-1},
  author={Ruediger Staubert and Dmitry Klochkov and Vadim Vybornov and J{\"o}rn Wilms and Fiona A. Harrison},
  journal={arXiv: High Energy Astrophysical Phenomena},
  year={2016}
}
The centroid energy Ecyc of the cyclotron line in the spectrum of the binary X-ray pulsar Her X-1 had been found to decrease with time on a time scale of a few tens of years - surprisingly short astrophysically. This was found for the pulse phase averaged line centroid energy using observational data from various X-ray satellites over the time frame 1996 to 2012, establishing a reduction of about 4 keV. Here we report on the result of a new observation by NuSTAR performed in August 2015. The… Expand

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  • 2019
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References

SHOWING 1-10 OF 40 REFERENCES
Long-term change in the cyclotron line energy in Hercules X-1
Aims. We investigate the long-term evolution of the cyclotron resonance scattering feature (CRSF) in the spectrum of the binary X-ray pulsar Her X-1 and present evidence of a true long-term decreaseExpand
Discovery of a flux-related change of the cyclotron line energy in Hercules X-1
Aims. We present the results of ten years of repeated measurements of the Cyclotron Resonance Scattering Feature (CRSF) in the spectrum of the binary X-ray pulsar Her X-1 and report the discovery ofExpand
Evidence for strong cyclotron line emission in the hard X-ray spectrum of Hercules X-1
We present further results of our Hercules X-1 balloon observation on 1976 May 3 which confirm the existence of a strong line feature at approx.58 keV in the pulsed (1.24s) X-ray spectrum we reportedExpand
No anticorrelation between cyclotron line energy and X-ray flux in 4U 0115+634
We report on an outburst of the high mass X-ray binary 4U 0115+634 with a pulse period of 3.6 s in 2008 March/April as observed with RXTE and INTEGRAL. During the outburst the neutron star’sExpand
Her X-1: the positive cyclotron line energy / luminosity correlation
Studies of some bright, super-Eddington transient pulsars show a negative correlation between the energy of the cyclotron resonance scattering feature (CRSF) and the bolometric luminosity. For HerExpand
Stability of the Cyclotron Resonance Scattering Feature in Hercules X-1 with RXTE
Five observations of the hard X-ray spectrum of Her X-1 from RXTE show that the ~41 keV energy of the cyclotron scattering line is constant within statistics of a few percent per observation. TheExpand
NuSTAR Discovery of a Luminosity Dependent Cyclotron Line Energy in Vela X-1
We present NuSTAR observations of Vela X-1, a persistent, yet highly variable, neutron star high-mass X-ray binary (HMXB). Two observations were taken at similar orbital phases but separated byExpand
4U 0115+63 from RXTE and INTEGRAL data: Pulse profile and cyclotron line energy
We analyze the observations of the transient X-ray pulsar 4U 0115+63 with the RXTE and INTEGRAL observatories in a wide X-ray (3–100 keV) energy band during its intense outbursts in 1999 and 2004.Expand
Pulse phase and precession phase resolved spectroscopy of Hercules X-1: studying a representative Main-On with RXTE
Aims. We performed a detailed pulse phase resolved spectroscopy of the accreting binary X-ray pulsar Her X-1 in the energy range 3.5–75 keV and have established pulse phase profiles for all spectralExpand
Variable pulse profiles of Hercules X-1 repeating with the same irregular 35 d clock as the turn-ons
The accreting X-ray pulsar Her X-1 shows two types of long-term variations, both with periods of ∼35 days: 1) turn-on cycles, a modulation of the flux, with a ten-day long main-on and a five-day longExpand
...
1
2
3
4
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