Padova-Asiago Supernova Group
Ejecta-CSM Interacting Supernovae

Interacting supernovae are characterized by spectra showing narrow lines in emission (with FWHM tanging from a few 100 to a few 1000 km/s) that are believed to arise in dense cocoons rigch of hydrogne (in SNe IIn) or helium (in SNe Ibn). This circumstellar medium (CSM) was lost by the progenitor star in the latest stages of its life (weeks to decades before the SN explosion) through stellar super-winds.

Although large mass loss can be produced via binary interaction, large eruptions in very massive stars can also generate dense and massive circumstellar environments. In fact, a fraction of SNe IIn has been shown to be produced in the explosion of luminous blue variable (LBV) stars (e.g., Gal-Yam et al. 2009, Nature, 462, 624), whilst SNe Ibn are thought to be associated with Wolf-Rayet (WR) stars that experienced major mass loss episodes a short time before their terminal explosion (e.g. Pastorello et al. 2007, Nature, 447, 829). Even more interestingly, it has been shown that a growing number of interacting SNe have been heralded by major optical outbursts occurred weeks to years before their explosion (see, the Giant LBV eruptions project). These pre-SN transients, in terms of energetics and spectral appearance, may mimic a true SN explosion, and for this reason they have been named as ``SN impostors''.
Studing the multi-wavelength evolution of interacting SNe allows us to infer information about .....
The example of an ideal monitoring campaign of a Type IIn SN is given in Fig. 1.

Fig. 1 The outstanding follow-up campaign of SN 2015da. Optical (top left) and near-infrared (bottol-left) light curves. Optical spectral sequence (top-right), and early (bottom-middle) and late (bottom-right) near-infrared spectra. The figures are taken from Tartaglia et al. 2020, A&A, 635, A39).

Leading researchers: L. Tartaglia, A. Pastorello, N. Elias-Rosa, A. Reguitti, Y.-Z. Cai, I. Salmaso, E. Cappellaro.

Collaborators: M. Fraser, E. Callis, S. J. Brennan, R. Kotak, S. Moran, G. Pignata, K. Misra, M. T. Botticella, G. Pignata.