The Unusual Super-Luminous Supernovae SN 2011kl and ASASSN-15lh

TL;DR

This study uses radiation hydrodynamics modeling to explore whether magnetar-powered mechanisms can explain the luminosity and light curves of two ultra-luminous supernovae, SN 2011kl and ASASSN-15lh, revealing the importance of progenitor mass and nickel content.

Contribution

The paper demonstrates that magnetar models can account for the observed properties of these super-luminous supernovae, emphasizing the role of hydrodynamic simulations in understanding their progenitors and central engines.

Findings

SN 2011kl's light curve is consistent with a magnetar power source plus some nickel.

ASASSN-15lh's light curve can be reproduced with a large progenitor mass (~6 M_sun) and magnetar input.

Hydrodynamic modeling is crucial for constraining magnetar and progenitor properties.

Abstract

Two recently discovered very luminous supernovae (SNe) present stimulating cases to explore the extents of the available theoretical models. SN 2011kl represents the first detection of a supernova explosion associated with an ultra-long duration gamma ray burst. ASASSN-15lh was even claimed as the most luminous SN ever discovered, challenging the scenarios so far proposed for stellar explosions. Here we use our radiation hydrodynamics code in order to simulate magnetar powered SNe. To avoid explicitly assuming neutron star properties we adopt the magnetar luminosity and spin-down timescale as free parameters of the model. We find that the light curve (LC) of SN 2011kl is consistent with a magnetar power source, as previously proposed, but we note that some amount of 56^Ni (> 0.08 M_sun) is necessary to explain the low contrast between the LC peak and tail. For the case of ASASSN-15lh we find physically plausible magnetar parameters that reproduce the overall shape of the LC provided the progenitor mass is relatively large (a mass of the ejecta approx 6 M_sun). The ejecta hydrodynamics of this event is dominated by the magnetar input, while the effect is more moderate for SN 2011kl. We conclude that a magnetar model may be used for the interpretation of these events and that the hydrodynamic modeling is necessary to derive the properties of powerful magnetars and their progenitors.