2003/12/31 by F. Haberl, V. E. Zavlin, J. Truemper +2 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1051/0004-6361:20034129
published as Astron.Astrophys. 419 (2004) 1077-1085 · Accepted for publication in A&A
arxiv created 2004/03/26 · openalex publication_date 2004/05/07 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
The XMM-Newton spectra of the isolated neutron star show deviations from a Planckian energy distribution below 400 eV, similar to the spectra of RBS1223, another long-period X-ray pulsar, as reported recently by [CITE]. For a Gaussian-shaped absorption line we derive an energy of 271 eV and an equivalent width of -40 eV from the phase-averaged spectra of . We investigate the spectral variations seen in hardness ratios as function of pulse phase and find that they are best described by changes in the depth of the absorption line. The line equivalent width changes between -31 eV around intensity maximum of the pulse and -58 eV at the declining part of the pulse. Small variations (<20 eV) of the line energy with pulse phase may still be caused by statistical fluctuations. On the other hand, the black-body temperature varies significantly by 2.5 eV (statistical 90% errors typically 0.7 eV) reaching the highest value at pulse maximum. One possible interpretation for the absorption line is cyclotron resonance scattering of protons in a magnetic field with G. This field strength is compatible with estimates inferred from recent spin down measurements of the pulsar.