Hidden shock powering the peak of SN 2020faa

Context. The link between the fate of the most massive stars and the resulting supernova (SN) explosion is still a matter of debate, in major part because of the ambiguity among light-curve powering mechanisms. When stars explode as SNe, the light-curve luminosity is typically sustained by a central engine (radioactive decay, magnetar spin-down, or fallback accretion). However, since massive stars eject considerable amounts of material during their evolution, there may be a significant contribution coming from interactions with the previously ejected circumstellar medium (CSM). Reconstructing the progenitor configuration at the time of explosion requires a detailed analysis of the long-term photometric and spectroscopic evolution of the related transient.
Aims: In this paper, we present the results of our follow-up campaign of SN 2020faa. Given the high luminosity and peculiar slow light curve, it is purported to have a massive progenitor. We present the spectro-photometric dataset and investigate different options to explain the unusual observed properties that support this assumption.
Methods: We computed the bolometric luminosity of the supernova and the evolution of its temperature, radius, and expansion velocity. We also fit the observed light curve with a multi-component model to infer information on the progenitor and the explosion mechanism.
Results: Reasonable parameters are inferred for SN 2020faa with a magnetar of energy, E_p = 1.5_−0.2^+0.5 × 10⁵⁰ erg, and spin-down time, t_spin = 15 ± 1 d, a shell mass, M_shell = 2.4_−0.4^+0.5 M_⊙, and kinetic energy, E_kin(shell) = 0.9_−0.3^+0.5 × 10⁵¹ erg, and a core with M_core = 21.5_−0.7^+1.4 M_⊙ and E_kin(core) = 3.9_−0.4^+0.1 × 10⁵¹ erg. In addition, we need an extra source to power the luminosity of the second peak. We find that a hidden interaction with either a CSM disc or several delayed and choked jets is a viable mechanism for supplying the required energy to achieve this effect.