Detecting emission lines with XMM-Newton in 4U 1538-52

作者：Rodes Roca J J^*; Page K L; Torrejon J M; O**orne J P; Bernabeu G

来源：Astronomy & Astrophysics, 2011, 526: A64.

DOI：10.1051/0004-6361/201014324

• X-rays: binaries
• pulsars: individual: 4U 1538-52

Context. The properties of the X-ray emission lines are a fundamental tool for studying the nature of the matter surrounding the neutron star and the phenomena that produce these lines.
Aims. The aim of this work is to analyse the X-ray spectrum of 4U 1538-52 obtained by the XMM-Newton observatory and to look for the presence of diagnostic lines in the energy range 0.3-11.5 keV.
Methods. We used a 54 ks PN & MOS/XMM-Newton observation of the high-mass X-ray binary 4U 1538-52 covering the orbital phase between 0.75 to 1.00 (the eclipse ingress). We modelled the 0.3-11.5 keV continuum emission with three absorbed power laws and looked for the emission lines.
Results. We found previously unreported recombination lines in this system at similar to 2.4 keV, similar to 1.9 keV, and similar to 1.3 keV, which is consistent with the presence of highly ionized states of S XV He alpha, Si XIII He alpha, and either Mg K alpha or Mg XI He alpha. On the other hand, in spectra that are both out of eclipse and in eclipse, we detect a fluorescence iron emission line at 6.4 keV, which is resolved into two components: a narrow (sigma <= 10 eV) fluorescence Fe K alpha line plus one hot line from highly photoionized Fe XXV.
Conclusions. The detection of new recombination lines during eclipse ingress in 4U 1538-52 indicates that there is an extended ionized region surrounding the neutron star.

• 出版日期2011-2