Evidence for strong cyclotron line emission in the hard X-ray spectrum of Hercules X-1

Abstract

view Abstract Citations (555) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence for strong cyclotron line emission in the hard X-ray spectrum of Hercules X-1. Truemper, J. ; Pietsch, W. ; Reppin, C. ; Voges, W. ; Staubert, R. ; Kendziorra, E. Abstract Further results of the balloon observation of Hercules X-1 on May 3, 1976, are presented which confirm the previously reported existence of a strong line feature at about 58 keV in the pulsed (1.24 s) X-ray spectrum. The spectral excess in the line region over the extrapolated continuum is 5 to 6 sigmas. The best estimate of the line flux and line width are 0.003 photon/sq cm per sec and less than about 12 keV, respectively. The most likely interpretation of this line is electron cyclotron emission at the fundamental frequency from the hot polar plasma of the rotating neutron star. The corresponding magnetic-field strength is 5.3 trillion gauss. A search for the second-harmonic cyclotron emission line in that part of the data showing the highest signal-to-noise ratio reveals a 3.3-sigma spectral enhancement near the predicted energy (110 keV). Implications of the line width and the line intensity ratio for the physical conditions of the emitting plasma and the beaming geometry are discussed. Publication: The Astrophysical Journal Pub Date: February 1978 DOI: 10.1086/182617 Bibcode: 1978ApJ...219L.105T Keywords: Cyclotron Radiation; Line Spectra; Neutron Stars; Pulsars; X Ray Spectra; X Ray Stars; Electron Emission; High Temperature Plasmas; Interstellar Magnetic Fields; Signal To Noise Ratios; Spectral Line Width; X Ray Astronomy; Space Radiation; Neutron Stars:X-Ray Sources; Spectra:X-Ray Sources full text sources ADS | data products SIMBAD (4)