Exploring the diversity of Type Ibc supernovae with ATLAS

Abstract

Type Ib and Type Ic supernovae are astrophysical transients resulting from the core collapse of envelope-stripped progenitor stars. Their evolution contributes substantially to kinetic, chemical, and radiative feedback, shaping their galactic environments. Throughout this thesis, I present spectrophotometric observations and modelling to investigate the properties and improve our understanding of Type Ibc supernovae. To date, only a single supernova has been shown to have periodic signals in its optical light curve: SN 2022jli. In this thesis, I present the discovery and detailed spectrophotometric follow-up observations of this first-of-a-kind supernova. I consider a range of plausible explanations, including interaction between the nascent neutron star and a companion, ultimately favouring interaction of the SN ejecta with nested dust shells. SN 2022jli represents the strongest evidence to date for a binary origin of a Type Ic supernova. I present detailed observations of SN 2023zaw, a member of the emerging ultra-stripped class of supernovae. These SNe have low ejecta masses, originating from progenitor stars stripped by a neutron star companion. I compare filtered photometry and (pseudo-)bolometric luminosities with a suite of models, finding evidence from the light curves of SN 2023zaw for the need for an additional, non-radioactive heating mechanism. Finally, expanding the scope to study the whole population, I have collated and analysed the largest systematic sample study of Type Ibc supernovae (N = 212 events). This analysis includes every SN Ibc discovered within a roughly seven-year time window and detected by the ATLAS survey. Our analysis shows, that in a magnitude-limited regime, many SN Ibc exceed the theoretical upper limit on the luminosity. However, this discrepancy disappears in a volume-limited comparison (d < 100Mpc), suggesting that selection effects are important in this comparison. Within the sample, I identify a new ultra-stripped supernova, SN 2020ksa, discovered in the archival data.

Date of Award	Jul 2026
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Northern Ireland Department for the Economy
Supervisor	Stephen Smartt (Supervisor), Matt Nicholl (Supervisor) & Stuart Sim (Supervisor)