Seeing double: the frequency and detectability of double-peaked superluminous supernova light curves

TL;DR

This study investigates the prevalence of double-peaked light curves in superluminous supernovae, finding that such features may be common and providing insights into their origins and underlying mechanisms.

Contribution

It presents a comprehensive analysis of Type Ic SLSNe light curves, demonstrating that double-peaked structures are likely ubiquitous and challenging existing interaction-powered models.

Findings

8 out of 14 SLSNe show early flux excess

Double-peaked structure consistent across multiple objects

Early bumps have similar properties suggesting common origin

Abstract

The discovery of double-peaked light curves in some superluminous supernovae offers an important new clue to their origins. We examine the published photometry of all Type Ic SLSNe, finding 14 objects with constraining data or limits around the time of explosion. Of these, 8 (including the already identified SN 2006oz and LSQ14bdq) show plausible flux excess at the earliest epochs, which deviate significantly (2-9$\sigma$) from polynomial fits to the rising light curves. Simple scaling of the LSQ14bdq data show that they are all consistent with a similar double-peaked structure. PS1-10pm provides multicolour UV data indicating a temperature of $T_{\rm bb}=25000\pm5000\,$K during the early `bump' phase. We find that a double-peak cannot be excluded in any of the other 6 objects, and that this behaviour may be ubiquitous. The homogeneity of the observed bumps is unexpected for interaction-powered models. Engine-powered models can explain the observations if all progenitors have extended radii or the central engine drives shock breakout emission several days after the supernova explosion.