Ja n 20 04 The X - ray and radio emission from SN 2002 ap : The importance of Compton scattering

The radio and X-ray observations of the Type Ic supernova SN 2002ap are modeled. We find that inverse Compton cooling by photospheric photons explains the observed steep radio spectrum, and also the X-ray flux observed by XMM. Thermal emission from the shock is insufficient to explain the X-ray flux. The radio emitting region expands with a velocity of ∼ 70, 000 km s −1. From the ratio of X-ray to radio emission we find that the energy densities of magnetic fields and relativistic electrons are close to equipartion. The mass loss rate of the progenitor star depends on the absolute value of ǫ B , and is given by ˙ M ≈