Abstract

Contributed Talk - Splinter CloseBinaries   (MW-0250)

3D MHD Simulations of Double ONe White Dwarf Mergers

Giovanni Stimamiglio, Rüdiger Pakmor, Stephen Justham, Selma E. de Mink
Max Planck Institute for Astrophysics

Merging double white dwarfs (WDs) are a common endpoint of binary evolution and potential progenitors of Type Ia supernovae, neutron stars, and gravitational wave sources. While simulations of CO and He WD mergers have been widely explored in the literature, more massive double ONe WD mergers remain largely uncharted. The rate of such mergers has been predicted to reach $sim 1\%$ of the empirical volumetric rate of Type Ia SNe, due to dynamical effects in dense stellar environments like globular clusters. We present the first 3D magnetohydrodynamic simulations of double ONe WD mergers. Using the moving-mesh code AREPO, we follow the system from pre-coalescence through merger and several hundred rotational periods of the remnant, tracking magnetic field amplification and dynamical impact. We investigate the super-Chandrasekhar mass product, initially supported by differential rotation, which evolves under efficient magnetic angular momentum transport driven by dynamo processes. This will eventually lead to contraction and collapse to a neutron star. We assess whether ONe WD merger remnants retain strong magnetic fields up to collapse and produce magnetars. This scenario further positions ONe WD mergers as a compelling channel for fast radio bursts (FRBs) in old stellar populations.