Long-term evolution of the neutron-star spin period of SXP 1062
R. Sturm, F. Haberl, L. M. Oskinova, M. P. E. Schurch, V. Henault-Brunet, J. S. Gallagher III, A. Udalski
The Be/X-ray binary SXP1062 is of especial interest owing to the large
spin period of the neutron star, its large spin-down rate, and the
association with a supernova remnant constraining its age. This makes
the source an important probe for accretion physics. To investigate the
long-term evolution of the spin period and associated spectral
variations, we performed an XMM-Newton target-of-opportunity observation
of SXP1062 during X-ray outburst. Spectral and timing analysis of the
XMM-Newton data was compared with previous studies, as well as
complementary Swift/XRT monitoring and optical spectroscopy with the
SALT telescope were obtained. The spin period was measured to be P_s
=(1071.01+-0.16) s on 2012 Oct 14. The X-ray spectrum is similar to that
of previous observations. No convincing cyclotron absorption features,
which could be indicative for a high magnetic field strength, are found.
The high-resolution RGS spectra indicate the presence of emission lines,
which may not completely be accounted for by the SNR emission. The
comparison of multi-epoch optical spectra suggest an increasing size or
density of the decretion disc around the Be star. SXP1062 showed a net
spin-down with an average of (2.27+-0.44) s/yr over a baseline of 915
days.
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