Irene Salmaso, University of Padova / ESO Garching  - July 25th, 2022

Interacting supernovae (SNe) are very intriguing transients. In most cases, they are thought to arise from massive progenitor stars, which eject large amounts of matter during their life, producing a dense circumstellar medium. The interaction between the SN ejecta and this material produces energetic shock waves, where cosmic particles are accelerated and, possibly, some of the IceCube high-energy neutrinos are produced. The explosion of such massive stars may also lead to the formation of a massive black hole. When this is part of a binary system in which the companion is another compact object, the system will become a source of gravitational waves that will cause, sooner or later, the merging of the two objects. Mass-loss, rotation, interactions during common envelope phase and dynamical interactions heavily influence the evolution of compact binaries. Large uncertainties in the contribution of the different components significantly affects model prediction, highlighting the need of tighter observational constraint. In my talk I will show how the spectrophotometric study of a sample of well studied interacting SNe can provide information on the energy and chemical composition for both the SN ejecta and the circumstellar medium. In addition, I will discuss how this can shed light on the yet enigmatic explosion mechanism and the nature of the compact remnant.