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Detection of a cyclotron line and its second harmonic in 4U1907+09

G. Cusumano·T. Di Salvo·L. Burderi·M. Orlandini·S. Piraino·N. Robba·A. Santangelo
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Abstract

We report the detection of a cyclotron absorption line and its second harmonic in the average spectrum of the high mass X-ray binary 4U1907+09 observed by the BeppoSAX satellite on 1997 September 27 and 28. The broad band spectral capability of BeppoSAX allowed a good determination of the continuum against which the two absorption features are evident at ~ 19 and ~ 39 keV. Correcting for the gravitational redshift of a ~ 1.4 solar mass neutron star, the inferred surface magnetic field strength is B = 2.1 10E12 G that is typical for this kind of systems. We also detected an iron emission line at ~ 6.4 keV, with an equivalent width of ~ 60 eV.

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G. Cusumano, T. Di Salvo, L. Burderi, M. Orlandini, S. Piraino, N. Robba, A. Santangelo. 1998-09-14. Detection of a cyclotron line and its second harmonic in 4U1907+09. https://arxiv.org/abs/astro-ph/9809167

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