The X-ray spectrum and light curve of Supernova 1995N

We report on multi-epoch X-ray observations of the Type IIn (narrow emission line) Supernova (SN) 1995N with the ROSAT and ASCA satellites. The 1998 January ASCA X-ray spectrum is well fitted by a thermal bremsstrahlung (kT ∼ 10 keV, N_H ∼ 6 × 10²⁰ cm^-2) or power-law (α ∼ 1.7, W_H ∼ 10²¹ cm^-2) model. The X-ray light curve shows evidence for significant flux evolution between 1996 August and 1998 January: the count rate from the source decreased by 30 per cent between our 1996 August and 1997 August ROSAT observations, and the X-ray luminosity most likely increased by a factor of ∼2 between our 1997 August ROSAT and 1998 January ASCA observations, although evolution of the spectral shape over this interval is not ruled out. The high X-ray luminosity, L_X ∼ 10⁴¹ erg s^-1, places SN 1995N in a small group of Type Un supernovae with strong circumstellar interaction, and the evolving X-ray luminosity suggests that the circumstellar medium is distributed inhomogeneously.