IISER MOHALI

Abstract: Most massive stars conclude their lives in a violent core-collapse supernova (SN). A rare subset—superluminous supernovae (SLSNe)—exceed the luminosities of canonical core-collapse events by factors of 10–100. Although substantial progress has been made over the past decade in characterizing their observational properties, the physical mechanisms powering SLSNe and the nature of their progenitors remain open questions. In this seminar, I will provide a detailed overview of recent developments, including powering mechanisms such as magnetar spin-down, circumstellar interaction, and hybrid scenarios—emphasizing how each seeks to reproduce their extreme luminosities and diverse light-curve morphologies. I will discuss spectroscopic diagnostics that probe the composition and ionization of ejecta, with particular attention to emerging helium signatures in events traditionally regarded as hydrogen- and helium-poor. I will also examine the increasing number of SLSNe exhibiting light-curve undulations (“bumps”) and explore their potential origins in progenitor mass-loss histories, structured circumstellar media, or engine-driven variability. Recent observations of SN 2024ahr, SN 2024rmj, and SN 2024afav provide new constraints on helium abundance, ejecta–CSM geometry, and the late-stage evolution of massive stars. Together, these developments refine our understanding of SLSN progenitors and motivate future progress enabled by upcoming wide-field surveys such as the Vera Rubin Observatory’s LSST.