* Astronomy

Title: XMM-Newton observation of MACHO 104.20906.960: a dwarf nova candidate with a 2 h period
Authors: A.A. Nucita, S. Carpano, F. De Paolis, G. Ingrosso, B.M.T. Maiolo, M. Guainazzi

The binaries known as cataclysmic variables are particular binary systems in which the primary star (a white dwarf) accretes material from a secondary via Roche-lobe mechanism. Usually, these objects have orbital period of a few hours so that a detailed temporal analysis can be performed. Here, we present Chandra  XMM-Newton observations of a dwarf nova candidate identified in the past by optical observations towards the galactic Bulge and labelled as MACHO 104.20906.960. After a spectral analysis, we used the Lomb-Scargle technique for the period search and evaluated the confidence level using Monte-Carlo simulations. In this case, we found that the X-ray source shows a period of 2.03_{-0.07}^{+0.09}  hours (3 \sigma error) so that it is most likely a system of interacting objects. The modulation of the signal was found with a confidence level of  > 99%. The spectrum can be described by a two thermal plasma components with X-ray flux in the 0.3--10 keV energy band of 1.77_{-0.19}^{+0.16}  x 10^{-13} erg s^{-1} cm^{-2}. We find that the distance of the source is approximately 1 kpc thus corresponding to a luminosity L_{X} ~= 2 x 10^{31} erg s^{-1}.

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