Volume 558, October 2013
|Number of page(s)||9|
|Section||Stellar structure and evolution|
|Published online||04 October 2013|
Swift J053041.9-665426, a new Be/X-ray binary pulsar in the Large Magellanic Cloud⋆
Max-Planck-Institut für extraterrestrische Physik,
2 School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, UK
Received: 22 July 2013
Accepted: 25 August 2013
Aims. We observed the newly discovered X-ray source Swift J053041.9-665426in the X-ray and optical regime to confirm its proposed nature as a high mass X-ray binary.
Methods. We obtained XMM-Newton and Swift X-ray data, along with optical observations with the ESO Faint Object Spectrograph, to investigate the spectral and temporal characteristics of Swift J053041.9-665426.
Results. The XMM-Newton data show coherent X-ray pulsations with a period of 28.77521(10) s (1σ). The X-ray spectrum can be modelled by an absorbed power law with photon index within the range 0.76 to 0.87. The addition of a black body component increases the quality of the fit but also leads to strong dependences of the photon index, black-body temperature and absorption column density. We identified the only optical counterpart within the error circle of XMM-Newton at an angular distance of ~0.8′′, which is 2MASS J05304215-6654303. We performed optical spectroscopy from which we classify the companion as a B0-1.5Ve star.
Conclusions. The X-ray pulsations and long-term variability, as well as the properties of the optical counterpart, confirm that Swift J053041.9-665426 is a new Be/X-ray binary pulsar in the Large Magellanic Cloud.
Key words: galaxies: individual: Large Magellanic Cloud / X-rays: binaries / stars: emission-line, Be / stars: neutron / pulsars: individual: Swift J053041.9-665426
© ESO, 2013
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