Wednesday

The discovery of superluminous supernovae (SLSNe) is one of the major results of recent synoptic sky surveys. However, the rarity of nearby SLSNe has meant that most studies focus on the properties close to maximum light. Studying these events at later times, when possible, has significant advantages: as the ejecta eventually become transparent, we can see more directly the composition and structure, along with vital clues to the power source(s).

I will present a detailed analysis using a sample of 41 late-time spectra of 12 low-redshift SLSNe. Mean properties are compared to other SN sub-types and the key emission lines are identified. The line velocities and luminosity ratios are used to map the structure of the ejecta. Principle component and clustering analyses are performed to characterise the diversity within the population, and to test prospects for classifying SLSNe discovered only well after maximum light.

For one event in the sample, spectroscopic coverage -- along with HST / VLA / XMM imaging -- extends to 1000 days after explosion. I will discuss these data in the context of competing explosion models.