2023PASJ...75L..19T

Some hydrogen-poor supernovae (SNe) are found to undergo interaction with dense circumstellar matter (CSM) that may originate from mass eruption(s) just prior to core-collapse. We model the interaction between the remaining star and the bound part of the erupted CSM that eventually falls back to the star. We find that while fallback initially results in a continuous CSM down to the star, feedback processes from the star can push the CSM to large radii of ≳10¹⁵ cm for several years after the eruption. In the latter case, a tenuous bubble surrounded by a dense and detached CSM extending to ≳10¹⁶ cm is expected. Our model offers a natural unifying explanation for the diverse CSM structures seen in hydrogen-poor SNe, such as Type Ibn/Icn SNe that show CSM signatures soon after explosion, and the recently discovered Type Ic SNe 2021ocs and 2022xxf (the “Bactrian”) with CSM signatures seen only at late times.