Speaker
Description
Identifying the progenitors of rapidly rotating core-collapse supernovae (CCSNe) is crucial for understanding the formation of magnetars and the origin of long gamma-ray bursts. In this study, we investigated the evolution of mass-transferring binary systems in a low-metallicity environment ($Z = 10^{-3}$) using the MESA stellar evolution code. We explored a parameter space with initial mass ratios ($q$) from 0.5 to 0.8, orbital periods ($P_\mathrm{i}$) from 8 to 18 days, and donor star masses ($M_\mathrm{d,0}$) from 20 to $65 M_\odot$. By evolving these systems until the onset of core collapse, we compared their pre-supernova properties with single-star models. We found that the accretor stars bifurcate into two distinct evolutionary pathways. A fraction of the accretors undergo Chemically Homogeneous Evolution (CHE) due to efficient rotational mixing; these B-CHE models achieve extremely compact structures, maintaining core rotation rates ($\omega_c$) and $T/|W|$ ratios nearly an order of magnitude higher than single-star baselines. Conversely, for accretors that follow standard evolution (B-Std) and retain a hydrogen envelope, we demonstrate that a subsequent Common Envelope (CE) phase can rescue their angular momentum. If the post-CE stripped star enters a tight orbit ($P_\mathrm{CE} \le 0.5$ days) with a companion, robust tidal synchronization can spin up the core to rotation rates that rival or even exceed those of the CHE models. Ultimately, our results highlight that binary interactions—through either mass-accretion-induced CHE or post-CE tidal locking—are highly effective and necessary channels for producing the fast-rotating cores.
| Participate the oral/poster presentation award competition | Yes |
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