An Analysis of Late-Time Rebrightening in Stripped-Envelope Supernovae in Search of Circumstellar Material Interaction 72 views

Supernovae (SNe) have occurred throughout the majority of the time the universe has existed. They are violent explosions that affect the evolution of stars, heavy element abundance, neutron star and black hole development, and galaxy formation among other subjects. Core collapse SNe (CCSNe) occur when stars larger than 8 solar masses reach the end of their lifespan. Stripped-envelope SNe (SESNe), as a subcategory of CCSNe, occur when their progenitors have lost matter prior to explosion. This matter could surround the star and become circumstellar material (CSM), but this is far from a guarantee as other progenitor mechanisms may displace the lost matter. If this does occur, however, the SESN ejecta would run into its CSM and cause a photometric bump, what is dubbed a “rebrightening.” In this thesis, I aim to find evidence of rebrightening in the light curves of SESNe due to CSM interaction at late times. Utilizing archival data from the Zwicky Transient Facility (ZTF) and Asteroid Terrestrial-impact Last Alert System (ATLAS), I analyze their visible-NIR light curves for 39 SESNe in a volume-limited (z<0.01) sample. 15 of them exhibit real consecutive detections 400+ days after their peak, as determined through my analysis pipeline. While this light may not be due to CSM interaction or emitted by the SN itself, the occurrence of late-time rebrightening signals imply a useful detection method in this pipeline. By studying other methods of detection and verification, this procedure can become a sound method for CSM interaction identification and further define what we know about SESNe.

BS (Bachelor of Science)

Time Domain Astrophysics; Supernovae; Stripped Envelope Supernovae; Circumstellar Material

English

2026-05-14