Effects of Light Echoes on the Luminosity and Spectra of Type Ia Supernovae

Abstract

The occurrence of a light echo associated with the outburst of V838 Mon has clearly shown what effects one is to expect when a rapid radiation transient illuminates a neighboring dust cloud. The radiation source being a galactic object, in this particular case we have been able to disentangle the scattered radiation from that directly emitted by the outbursting star. This is not the case when the same phenomenon takes place Mpc away from us, like in the case of an extragalactic Supernova, where we cannot tell the light echo contribution from the genuine supernova radiation.Here I briefly revise the effects of scattered light echoes on the luminosity and spectral appearance of Type Ia Supernovae, a class of objects which is fundamental in the so‐called precision Cosmology, but for which we still lack a full understanding. In this context I discuss the potential role of light echoes in clarifying the Type Ia progenitor’s nature and I present very recent high resolution spectroscopy data obtained for SN 2006X, which seem to indicate the presence of neutral gas in the immediate surroundings of the explosion.