Tracing superluminous supernovae through time: Progenitor mass loss and spectroscopic diversity

by Anamaria Gkini (Stockholm University)

Friday 26 Sept 2025, 10:30 → 11:30 Europe/Stockholm

FC61 (AlbaNova Main Building)

The fate of massive stars and the type of supernova (SN) they produce are closely tied to their final stages of evolution. In these late phases, stars can experience eruptive mass loss, forming circumstellar material (CSM) that can leave observable signatures in SN spectra, particularly as resonance lines in the near-ultraviolet (NUV).

In this seminar, I will present my PhD work on superluminous supernovae (SLSNe), an exceptionally bright class of SNe, with a focus on NUV spectroscopy to search for evidence of recently ejected CSM shells. I will first discuss two SLSNe where CSM shells were detected, inferring their properties and the timing of the ejection. I will then expand to the full sample, modeling the spectral regions where CSM-related lines are expected to assess the occurrence and properties of fast-moving CSM shells.

These results provide insight into eruptive mass-loss mechanisms in the final stages of stellar evolution and help constrain the nature of SLSN progenitors. Finally, I will highlight a single object from the SLSN sample with particularly intriguing spectral lines, illustrating the diversity that exists even within this rare class of SNe.