Simultaneous XMM-Newton and ESO VLT observations of supernova 1995N: probing the wind-ejecta interaction

We present the results of the first XMM-Newton observation of the interacting Type IIn supernova 1995N, performed in 2003 July. We find that the 0.2-10.0 keV unabsorbed flux dropped to a value of ~=1.8 × 10^-13ergcm^-2s^-1, almost one order of magnitude lower than that of a previous ASCA observation of 1998 January. From all the available X-ray measurements, an interesting scenario emerges where the X-ray light emission may be produced by two-phase (clumpy/smooth) circumstellar material. The X-ray spectral analysis shows statistically significant evidence for the presence of two distinct components, which can be modelled with emission from optically thin, thermal plasmas at different temperatures. The exponent of the ejecta density distribution inferred from these temperatures is n~= 6.4. From the fluxes of the two spectral components, we derive an estimate of the mass-loss rate of the supernova progenitor, , at the upper end of the interval exhibited by red supergiants. Coordinated optical and infrared observations allow us to reconstruct the simultaneous infrared to X-ray flux distribution of SN 1995N. We find that, at ~9 yr after explosion, the direct X-ray thermal emission due to the wind-ejecta interaction is ~5 times larger than the total reprocessed infrared/optical flux.