SXP1062 in outburst
R. Sturm (MPE, Garching), L. M. Oskinova (Institute for Physics and Astronomy, University Potsdam), F. Haberl (MPE),  Y.-H. Chu (Department of Astronomy, University of Illinois), V. Henault-Brunet (University of Surrey), J. Gallagher (Department of Astronomy, University of Wisconsin-Madison), M. A. Guerrero (Instituto de Astrofisica de Andalucia, IAA-CSIC), S. Popov (Sternberg Astronomical Institute, Moscow State University), M. Schurch (University of Cape Town)
We report a new X-ray outburst of SXP1062, a Be/X-ray binary associated with a supernova remnant and located in the Wing of the Small Magellanic Cloud. In a 2195 s Swift/XRT observation (ObsID 00091814001) starting on 2014-06-01 09:44 (UT), the source was detected with 608±25 raw background-subtracted counts. The Swift/XRT spectra can be described well by an absorbed power law with a photon index of Γ=0.70±0.13. For the SMC column density, we obtain an upper limit of NH< 1.6 × 1021 cm-2. The SMC absorption was modelled with SMC abundance set to 0.2 Zsolar for elements heavier than helium. An additional Galactic foreground absorption was set to 6 × 1020 cm-2. We derive an observed flux of 24.5±2.5 × 10-12 erg cm-2 s-1 in the 0.2-10.0 keV band corresponding to an unabsorbed luminosity of 1.09 × 1037 erg s-1 (assuming a distance of 60 kpc). This is the highest X-ray luminosity observed from SXP1062 so far. The spectral shape is consistent with that seen during the previous outburst in Oct. 2012 (Sturm et al. 2013, A&A 556, A139) The preceding Swift observation (ObsID 00032580059) was obtained on 2014-05-18 02:00 with the XRT exposure time of 1561 s. The count rate was below 0.0056 cts s-1, i.e. a factor of 50 fainter than in the most recent observation we report here. The elapsed time between this outburst and two previous outbursts seen in the optical I band is consistent, strongly supporting the orbital period interpretation by Schmidtke et al. (ATel #4596). Therefore, the currently ongoing outburst is likely of type-I and we expect an optical/NIR outburst as well. We will follow this outburst with a sequence of Chandra and SALT observations. All uncertainties are given for 90% confidence. We acknowledge the use of public data from the Swift data archive and thank the Swift team for accepting and scheduling the target of opportunity observation.
optical,x-ray,binary,neutron star,pulsar,star,supernova remnant,supernovae,transient