Cyclotron absorption lines in the era of Suzaku and NuSTAR
arXiv:1705.05536
Abstract
Cyclotron resonance scattering features or cyclotron absorption lines are unique features observed in the hard X-ray spectra of accretion powered X-ray pulsars with magnetic field of the order of 10 G. Detection of these features enables us for the direct estimation of strength of the magnetic field close to the neutron star surface. Corresponding to magnetic field of 10 G, the fundamental cyclotron lines are expected in 10-100 keV energy range with harmonics expected at multiples of fundamental line energy. However, we detected first harmonic of cyclotron line at less than twice of the fundamental line energy (1.7 times the fundamental line energy) in Be/X-ray binary pulsar Cep X-4. With the broadband spectral capability of and observatories, we have investigated cyclotron resonance scattering features in several X-ray pulsars to understand the shape of the lines, width, magnetic field mapping, anharmonicity in the line energies and luminosity-dependent properties of cyclotron lines. The results obtained from these works and new detection of cyclotron line in unknown/poorly studied sources are presented in this paper.
4 pages, 3 figures, 1 table; Proceedings of the conference '7 years of MAXI: monitoring X-ray transients', RIKEN, Saitama, Japan