The cyclotron line energy in Her X-1: stable after the decay
| dc.contributor.author | Staubert, R. | |
| dc.contributor.author | Ducci, L. | |
| dc.contributor.author | Ji, L. | |
| dc.contributor.author | Fürst, F. | |
| dc.contributor.author | Wilms, J. | |
| dc.contributor.author | Rothschild, R.E. | |
| dc.contributor.author | Pottschmid, K. | |
| dc.contributor.author | Brumback, M. | |
| dc.contributor.author | Harrison, F. | |
| dc.date.accessioned | 2021-01-26T17:38:14Z | |
| dc.date.available | 2021-01-26T17:38:14Z | |
| dc.date.issued | 2020-08-17 | |
| dc.description.abstract | We summarize the results of a dedicated effort between 2012 and 2019 to follow the evolution of the cyclotron line in Her~X-1 through repeated NuSTAR observations. The previously observed nearly 20-year long decay of the cyclotron line energy has ended around 2012: from there onward the pulse phase averaged flux corrected cyclotron line energy has remained stable and constant at an average value of Ecyc= (37.44+/-0.07) keV (normalized to a flux level of 6.8 RXTE/ASM-cts/s). The flux dependence of Ecyc discovered in 2007 is now measured with high precision, giving a slope of (0.675+/-0.075) keV/(ASM-cts/s), corresponding to an increase of 6.5% of Ecyc for an increase in flux by a factor of two. We also find that all line parameters as well as the continuum parameters show a correlation with X-ray flux. While a correlation between Ecyc and X-ray flux (both positive and negative) is now known for several accreting binaries with various suggestions for the underlying physics, the phenomenon of a long-term decay has so far only been seen in Her~X-1 and Vela~X-1, with far less convincing explanations. | en |
| dc.description.sponsorship | We would like to acknowledge the dedication of all the people who have contributed to the great success of all relevant missions, in particular NuSTAR. We especially thank the “schedulers”, foremost Karl Forster, for his efforts with respect to the non-standard scheduling of the observations of Her X-1. We acknowledge the historical contributions to the subject at hand by Dmitry Klochkov. We thank the anonymous referee for valuable comments. | en |
| dc.description.uri | https://arxiv.org/abs/2008.13434 | en |
| dc.format.extent | 13 pages | en |
| dc.genre | journal articles | en |
| dc.identifier | doi:10.13016/m2yog2-cjcb | |
| dc.identifier.citation | R. Staubert, L. Ducci, L. Ji, F. Fürst, J. Wilms, R.E. Rothschild, K. Pottschmidt, M. Brumback and F. Harrison, The cyclotron line energy in Her X-1: stable after the decay, https://arxiv.org/abs/2008.13434 | en |
| dc.identifier.uri | http://hdl.handle.net/11603/20618 | |
| dc.language.iso | en | en |
| dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
| dc.relation.ispartof | UMBC Center for Space Sciences and Technology | |
| dc.relation.ispartof | UMBC Faculty Collection | |
| dc.relation.ispartof | UMBC Physics Department | |
| dc.rights | This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author. | |
| dc.rights | c ESO 2020 | |
| dc.subject | magnetic fields | en |
| dc.subject | neutron stars | en |
| dc.subject | radiation mechanisms | en |
| dc.subject | cyclotron scattering features | en |
| dc.subject | accretion | en |
| dc.subject | accretion columns | en |
| dc.subject | binaries | en |
| dc.subject | eclipsing | en |
| dc.subject | stars | en |
| dc.title | The cyclotron line energy in Her X-1: stable after the decay | en |
| dc.type | Text | en |