Triggering electron capture supernovae: Dark matter effects in degenerate white-dwarf-like cores of super-asymptotic giant branch stars

Electron-capture supernovae (ECSNe) have emerged as a compelling formation channel for low-mass neutron stars, bolstered by decades of theoretical work and increasingly supported by observational evidence, including the recent identification of SN 2018zd. Motivated by this, we investigate the influence of fermionic asymmetric dark matter (ADM) on the equilibrium structure of progenitor cores and the formation of their neutron star remnants. Using a general relativistic two-fluid formalism, we model the coupled evolution of ordinary matter (OM) and ADM, treated as separately conserved fluids interacting solely through gravity. Our analysis focuses on neon-rich white dwarfs (Ne WDs), which are typical progenitor cores for ECSNe. We assume conservation of both baryon number (NB) and DM particle number (ND) during collapse, allowing for a consistent mapping between progenitor and remnant configurations. We find that ADM significantly enhances the central density of the WD progenitor. This lowers the threshold gravitational mass M⁎ required to initiate electron capture, enabling ECSNe from lower-mass progenitors. The resulting remnants are stable, DM-admixed neutron stars with gravitational masses potentially well below current observational bounds. Moreover, we find that the conversion energy during the WD-to-NS conversion is also significantly reduced for higher ADM particle masses and fractions, suggesting that unusually low-energy ECSNe may serve as potential indicators of ADM involvement in stellar collapse.