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

Journal article
(Original article)

Publication Details

Author(s): Staubert R, Klochkov D, Vybornov V, Wilms J, Harrison FA
Journal: Astronomy & Astrophysics
Publisher: EDP Sciences
Publication year: 2016
Volume: 590
ISSN: 1432-0746


The centroid energy E of the cyclotron line in the spectrum of the binary X-ray pulsar Her X-1 has been found to decrease with time on a time scale of a few tens of years - surprisingly short in astrophysical terms. This was found for the pulse phase-averaged line centroid energy using observational data from various X-ray satellites over the time period 1996 to 2012, establishing a reduction of ∼4 keV. Here we report on the result of a new observation by NuSTAR performed in August 2015. The earlier results are confirmed and strengthened with respect to both the dependence of E on flux (it is still present after 2006) and the dependence on time: the long-term decay continued with the same rate, corresponding to a reduction of ∼5 keV in 20 yr.

FAU Authors / FAU Editors

Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik

External institutions with authors

California Institute of Technology (Caltech)
Eberhard Karls Universität Tübingen

How to cite

Staubert, R., Klochkov, D., Vybornov, V., Wilms, J., & Harrison, F.A. (2016). Continued decay in the cyclotron line energy in Hercules X-1. Astronomy & Astrophysics, 590.

Staubert, R., et al. "Continued decay in the cyclotron line energy in Hercules X-1." Astronomy & Astrophysics 590 (2016).


Last updated on 2018-12-11 at 20:50