Cyclotron lines in highly magnetized neutron stars

Journal article

Publication Details

Author(s): Staubert R, Truemper J, Kendziorra E, Klochkov D, Postnov K, Kretschmar P, Pottschmidt K, Haberl F, Rothschild RE, Santangelo A, Wilms J, Kreykenbohm I, Furst F
Journal: Astronomy & Astrophysics
Publication year: 2019
Volume: 622
ISSN: 1432-0746


Cyclotron lines, also called cyclotron resonant scattering features are spectral features, generally appearing in absorption, in the X-ray spectra of objects containing highly magnetized neutron stars, allowing the direct measurement of the magnetic field strength in these objects. Cyclotron features are thought to be due to resonant scattering of photons by electrons in the strong magnetic fields. The main content of this contribution focusses on electron cyclotron lines as found in accreting X-ray binary pulsars (XRBP) with magnetic fields on the order of several 10(12) Gauss. Also, possible proton cyclotron lines from single neutron stars with even stronger magnetic fields are briefly discussed. With regard to electron cyclotron lines, we present an updated list of XRBPs that show evidence of such absorption lines. The first such line was discovered in a 1976 balloon observation of the accreting binary pulsar Hercules X-1, it is considered to be the first direct measurement of the magnetic field of a neutron star. As of today (end 2018), we list 35 XRBPs showing evidence of one ore more electron cyclotron absorption line(s). A few have been measured only once and must be confirmed (several more objects are listed as candidates). In addition to the Tables of objects, we summarize the evidence of variability of the cyclotron line as a function of various parameters (especially pulse phase, luminosity and time), and add a discussion of the di ff erent observed phenomena and associated attempts of theoretical modeling. We also discuss our understanding of the underlying physics of accretion onto highly magnetized neutron stars. For proton cyclotron lines, we present tables with seven neutron stars and discuss their nature and the physics in these objects.

FAU Authors / FAU Editors

Kreykenbohm, Ingo Dr.
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik

External institutions with authors

Eberhard Karls Universität Tübingen
European Space Agency (ESA)
Lomonosov Moscow State University / Московский государственный университет имени М.В.Ломоносова
Max-Planck-Institut für extraterrestrische Physik (MPE) / Max Planck Institute for Extraterrestrial Physics
National Aeronautics and Space Administration (NASA)
University of California, San Diego

How to cite

Staubert, R., Truemper, J., Kendziorra, E., Klochkov, D., Postnov, K., Kretschmar, P.,... Furst, F. (2019). Cyclotron lines in highly magnetized neutron stars. Astronomy & Astrophysics, 622.

Staubert, R., et al. "Cyclotron lines in highly magnetized neutron stars." Astronomy & Astrophysics 622 (2019).


Last updated on 2019-07-06 at 09:53