An overly-luminous Type II supernova from a massive progenitor
Bose, S. et al., 2021, MNRAS, 503, 3472
ASASSN-18am/2018gk is a newly discovered member of the rare group of luminous, hydrogen-rich supernovae with a peak absolute magnitude of \(M_V \approx -20\) mag that is in between normal core-collapse SNe and superluminous SNe, which was also considered as a missing gap by some earlier studies.
Only about five such supernovae have been identified so far, which also includes our previously discovered ASASSN-15nx (Bose, S. et al., 2018b, ApJ, 862, 107). The high intrinsic luminosity (without circumstellar interaction) of these supernovae makes it difficult or impossible to explain by widely accepted neutrino driven explosion mechanism. In this work, we examine various powering mechanisms, including radiative diffusion and magentar spindown models.…