Inversion of the decay of the cyclotron line energy in Her X-1
arXiv:1710.05150 · doi:10.1051/0004-6361/201731927
Abstract
Recent observations of Her X-1 with NuSTAR and INTEGRAL in 2016 have provided evidence that the 20-year decay of the cyclotron line energy found between 1996 and 2015 has ended and that an inversion with a new increase, possibly similar to the one observed around 1990-1993, has started. We consider this a strong motivation for further observations and for enhanced efforts to significantly improve our theoretical understanding of the accretion process in binary X-ray pulsars. We speculate about the physics behind the long-term decay and its inversion, a possible cyclic behavior, and correlations with other variable observables.
arXiv comment5 pages, 1 figure, accepted by A&A
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