SUZAKU OBSERVATION OF THE CLASSICAL NOVA V2491 Cyg IN QUIESCENCE

We present the Suzaku XIS observation of V2491 Cyg (Nova Cyg 2008 No. 2) obtained in quiescence, more than two years after the outburst. The nova was detected as a very luminous source in a wide spectral range from soft to hard X-rays. A very soft blackbody-like component peaking at 0.5 keV indicates that we observe either remaining, localized hydrogen burning on the surface of the white dwarf, or accretion onto a magnetized polar cap. In the second case, V2491 Cyg is a candidate "soft intermediate polar." We obtained the best fit for the X-ray spectra with several components: two of thermal plasma, a blackbody and a complex absorber. The latter is typical of intermediate polars. The X-ray light curve shows a modulation with a period of similar to 38 minutes. The amplitude of this modulation is strongly energy-dependent and reaches a maximum in the range 0.8-2.0 keV. We discuss the origin of the X-ray emission and pulsations, and the likelihood of the intermediate polar scenario.