English

The continued spectral and temporal evolution of RX J0720.4-3125

High Energy Astrophysical Phenomena 2015-06-04 v1

Abstract

RX J0720.4-3125 is the most peculiar object among a group of seven isolated X-ray pulsars (the so-called "Magnificent Seven"), since it shows long-term variations of its spectral and temporal properties on time scales of years. This behaviour was explained by different authors either by free precession (with a seven or fourteen years period) or possibly a glitch that occurred around MJD=52866±73days\mathrm{MJD=52866\pm73 days}. We analysed our most recent XMM-Newton and Chandra observations in order to further monitor the behaviour of this neutron star. With the new data sets, the timing behaviour of RX J0720.4-3125 suggests a single (sudden) event (e.g. a glitch) rather than a cyclic pattern as expected by free precession. The spectral parameters changed significantly around the proposed glitch time, but more gradual variations occurred already before the (putative) event. Since MJD53000days\mathrm{MJD\approx53000 days} the spectra indicate a very slow cooling by \sim2 eV over 7 years.

Keywords

Cite

@article{arxiv.1203.3708,
  title  = {The continued spectral and temporal evolution of RX J0720.4-3125},
  author = {Markus M. Hohle and Frank Haberl and Jacco Vink and Cor P. de Vries and Roberto Turolla and Silvia Zane and Mariano Méndez},
  journal= {arXiv preprint arXiv:1203.3708},
  year   = {2015}
}

Comments

seven pages, three figures, three tables; accepted by MNRAS