Long-term evolution of the neutron-star spin period of SXP 1062. (arXiv:1304.6022v1 [astro-ph.HE])

Long-term evolution of the neutron-star spin period of SXP 1062. (arXiv:1304.6022v1 [astro-ph.HE]):
The Be/X-ray binary SXP 1062 is of especial interest owing to the large spin
period of the neutron star, its large spin-down rate, and the correlation 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 SXP 1062 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. The spin period was measured to be P=(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 are found, constraining the magnetic
field of the neutron star. 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. SXP 1062
showed a net spin-down with an average of (2.27+-0.44) s/yr over a baseline of
915 days.