Extremely energetic supernova explosions embedded in a massive circumstellar medium: the case of SN 2016aps

TL;DR

This study uses radiation-hydrodynamic simulations to explain the extreme brightness of SN 2016aps as a hypernova explosion colliding with a massive circumstellar medium, revealing insights into very massive star deaths.

Contribution

It demonstrates that a hypernova ejecta colliding with a massive CSM can account for the observed properties of SN 2016aps, linking energetic supernovae to pre-explosion mass ejections in massive stars.

Findings

SN 2016aps explained by a 30 M_sun ejecta with 10^52 erg energy colliding with an 8 M_sun CSM.

Massive stars >40 M_sun may eject hydrogen-rich envelopes before core-collapse.

Provided relations between peak luminosity, radiated energy, and rise time for energetic interacting SNe.

Abstract

We perform one-dimensional radiation-hydrodynamic simulations of energetic supernova ejecta colliding with a massive circumstellar medium (CSM) aiming at explaining SN 2016aps, likely the brightest supernova observed to date. SN 2016aps was a superluminous Type-IIn SN, which released as much as $\gtrsim 5\times 10^{51}$ erg of thermal radiation. Our results suggest that the multi-band light curve of SN 2016aps is well explained by the collision of a $30\ M_\odot$ SN ejecta with the explosion energy of $10^{52}$ erg and a $\simeq 8\ M_\odot$ wind-like CSM with the outer radius of $10^{16}$ cm, i.e., a hypernova explosion embedded in a massive CSM. This finding indicates that very massive stars with initial masses larger than $40\ M_\odot$, which supposedly produce highly energetic SNe, occasionally eject their hydrogen-rich envelopes shortly before the core-collapse. We suggest that the pulsational pair-instability SNe may provide a natural explanation for the massive CSM and the energetic explosion. We also provide the relations between the peak luminosity, the radiated energy, and the rise time for interacting SNe with the kinetic energy of $10^{52}$ erg, which can be used for interpreting SN 2016aps-like objects in future surveys.