Modeling The Most Luminous Supernova Associated with a Gamma-Ray Burst, SN 2011kl

TL;DR

This study analyzes the luminous supernova SN 2011kl associated with a gamma-ray burst, exploring different models to explain its light curve features and suggesting a magnetar as the primary energy source.

Contribution

The paper reexamines the energy sources of SN 2011kl, demonstrating that different light curve features can be explained by magnetar and nickel models, including the early excess with shock cooling.

Findings

LCs without early excess fit magnetar+Ni models

LC with early excess explained by magnetar+Ni with shock cooling

SN 2011kl likely powered mainly by a nascent magnetar

Abstract

We study the most luminous known supernova (SN) associated with a gamma-ray burst (GRB), SN 2011kl. The photospheric velocity of SN 2011kl around peak brightness is $21,000\pm7,000$ km s$^{-1}$. Owing to different assumptions related to the light-curve (LC) evolution (broken or unbroken power-law function) of the optical afterglow of GRB 111209A, different techniques for the LC decomposition, and different methods (with or without a near-infrared contribution), three groups derived three different bolometric LCs for SN 2011kl. Previous studies have shown that the LCs without an early-time excess preferred a magnetar model, a magnetar+$^{56}$Ni model, or a white dwarf tidal disruption event model rather than the radioactive heating model. On the other hand, the LC shows an early-time excess and dip that cannot be reproduced by the aforementioned models, and hence the blue-supergiant model was proposed to explain it. Here we reinvestigate the energy sources powering SN 2011kl. We find that the two LCs without the early-time excess of SN 2011kl can be explained by the magnetar+$^{56}$Ni model, and the LC showing the early excess can be explained by the magnetar+$^{56}$Ni model taking into account the cooling emission from the shock-heated envelope of the SN progenitor, demonstrating that this SN might primarily be powered by a nascent magnetar.