Speaker
Description
The presence of dense circumstellar medium (CSM) around core-collapse supernova (SN) progenitors has been universally realized lately through the radiative properties of SN-CSM interaction immediately after the explosion, although the physical origin of the CSM formation has not yet been established. Recent detections of significant polarization in early-phase Type IIP SNe 2023ixf and 2024ggi have advocated the possibility of the aspherical distribution of the dense CSM, which could be a promising clue to understanding the mass-loss mechanism happening in the final phase of massive stars. Here, we note that simply raising the disk-like CSM originating from binary interaction can cause self-inconsistency between the progenitor-CSM setup and observational facts. Instead, we examine the alternative scenario of whether stellar rotation can affect the resultant CSM formation by considering trajectory alteration, stellar surface flattening, centrifugal force, and gravity darkening. We find that these stellar rotation effects will prominently emerge only when the stellar rotation speed is faster than $\sim20\%$ of the critical rotation. This rotation rate is even faster than possibly inferred for Betelgeuse. Explaning the polarization degree in SN 2023ixf and 2024ggi requires similarly fast stellar rotation for a single red supergiant. This indicates the plausibility of other scenarios for the aphserical CSM formation, including the spinning up of the progenitor star via stellar merger and intrinsically aspherical mass-loss activity.
| Participate the oral/poster presentation award competition | No |
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