• DOI:10.1051/0004-6361/201629744
• Corpus ID: 118371059

EXTraS discovery of two pulsators in the direction of the LMC: a Be/X-ray binary pulsar in the LMC and a candidate double-degenerate polar in the foreground

@article{Haberl2016EXTraSDO,
  title={EXTraS discovery of two pulsators in the direction of the LMC: a Be/X-ray binary pulsar in the LMC and a candidate double-degenerate polar in the foreground},
  author={Frank Haberl and Gian Luca Israel and G. A. Rodr{\'i}guez Castillo and Georgios Vasilopoulos and Corentin Delvaux and Andrea De Luca and Stefania Carpano and Paolo Esposito and Giovanni Novara and Ruben Salvaterra and Andrea Tiengo and Daniele D'Agostino and Andrzej Udalski},
  journal={Astronomy and Astrophysics},
  year={2016},
  volume={598}
}

• F. Haberl, G. Israel, +10 authors A. Udalski
• Published 4 October 2016
• Physics
• Astronomy and Astrophysics

Context. The Exploring the X-ray Transient and variable Sky (EXTraS) project searches for coherent signals in the X-ray archival data of XMM-Newton . Aims. XMM-Newton performed more than 400 pointed observations in the region of the Large Magellanic Cloud (LMC). We inspected the results of the EXTraS period search to systematically look for new X-ray pulsators in our neighbour galaxy. Methods. We analysed the XMM-Newton observations of two sources from the 3XMM catalogue which show significant signals for coherent pulsations. Results. 3XMM J051259.8-682640 was detected as a source with a hard X-ray spectrum in two XMM-Newton observations, revealing a periodic modulation of the X-ray flux with 956 s. As optical counterpart we identify an early-type star with H α emission. The OGLE I -band light curve exhibits a regular pattern with three brightness dips which mark a period of ~1350 d. The X-ray spectrum of 3XMM J051034.6-670353 is dominated by a super-soft blackbody-like emission component ( kT ~ 70 eV) which is modulated by nearly 100% with a period of ~1418 s. From GROND observations we suggest a star with r ′ = 20.9 mag as a possible counterpart of the X-ray source. Conclusions. 3XMM J051259.8-682640 is confirmed as a new Be/X-ray binary pulsar in the LMC. We discuss the long-term optical period as the likely orbital period which would be the longest known from a high-mass X-ray binary. The spectral and temporal properties of the super-soft source 3XMM J051034.6-670353 are very similar to those of RX J0806.3+1527 and RX J1914.4+2456 suggesting that it belongs to the class of double-degenerate polars and is located in our Galaxy rather than in the LMC.