Origin of postmaximum bump in luminous type Ic SN 2019stc

TL;DR

This paper investigates the origin of the postmaximum bump in the light curve of superluminous supernova SN 2019stc, proposing magnetar magnetic field enhancement as the cause rather than circumstellar interaction.

Contribution

It introduces a novel explanation for the postmaximum bump in superluminous supernovae, attributing it to magnetar dipole field amplification occurring months after explosion.

Findings

Magnetar dipole field amplifies by a factor of 2.8 at ~90 days

Circumstellar interaction is ruled out as the bump cause

Modeling supports magnetic field enhancement as the bump origin

Abstract

We address the issue of the postmaximum bump observed in the light curve of some superluminous supernovae. We rule out the popular mechanism of a circumstellar interaction suggested for the bump explanation. Instead we propose that the postmaximum bump is caused by the magnetar dipole field enhancement several months after the explosion. The modeling of SN 2019stc light curve based on the thin shell approximation implies that at the age of $\sim 90$ days the initial dipole magnetic field should be amplified by a factor of 2.8 to account for the postmaximum bump. The specific mechanism for the field amplification of the newborn magnetar on the timescale of several months has yet to be identified.