2024ApJ...977..118O

We investigate SN 2014C using three-dimensional (3D) hydrodynamic modeling, focusing on its early interaction with a dense circumstellar medium (CSM). Our objective is to uncover the pre-supernova (SN) CSM structure and constrain the progenitor star's mass-loss history prior to core collapse. Our comprehensive model traces the evolution from the progenitor star through the SN event and into the SN remnant phase. We simulate the remnant's expansion over approximately 15 yr, incorporating a CSM derived from the progenitor star's outflows through dedicated hydrodynamic simulations. Analysis reveals that the remnant interacted with a dense toroidal nebula extending from 4.3 × 10¹⁶ to 1.5 × 10¹⁷ cm in the equatorial plane, with a thickness of approximately 1.2 × 10¹⁷ cm. The nebula's density peaks at approximately 3 × 10⁶ cm^–3 at the inner boundary, gradually decreasing as ≈r^–2 at greater distances. This nebula formed due to intense mass loss from the progenitor star between approximately 5000 and 1000 yr before collapse. During this period, the maximum mass-loss rate reached about 8 × 10^–4M_⊙ yr^–1, ejecting ≈2.5 M_⊙ of stellar material into the CSM. Our model accurately reproduces Chandra and NuSTAR spectra, including the iron (Fe) K line, throughout the remnant's evolution. Notably, the Fe line is self-consistently reproduced, originating from shocked ejecta, with ≈0.05 M_⊙ of pure-Fe ejecta shocked during the remnant-nebula interaction. These findings suggest that the 3D geometry and density distribution of the CSM, as well as the progenitor star's mass-loss history, align with a scenario where the star was stripped through binary interaction, specifically common-envelope evolution.