Speaker
Description
We observe in nature overly luminous Type Ia supernovae which, if we take to have originated from the deflagration of a CO white dwarf, would imply a progenitor with a mass in excess of the Chandrasekhar mass. There are a number of possible mechanisms by which such a super-Chandrasekhar mass white dwarf may be supported. We consider the presence of a large (>10⁶ G) magnetic field in the white dwarf, the magnetic pressure from which provides necessary support to allow WDs to exist far above the Chandrasekhar mass, which we call "Highly magnetised white dwarfs", or B-WDs. To conduct simulations as part of Bhattacharya et al. (2021), we developed a heavily modified version of the STARS stellar evolution code (Eggleton (1971) and many updates since), incorporating prescriptions of Gupta et al. (2020) and Mukhopadhyay et al. (2021) to compute magnetic field strength at each calculation point in a WD model, along with the magnetic contributions to pressure and density.
We consider the possibility that this magnetic field support prescription can provide a mechanism to actually detonate super Chandrasekhar mass white dwarfs, and hence to produce overly luminous Type Ia supernovae. If we consider the decay of this magnetic field owing to Ohmic decay and Hall Drift, we obtain a possible trigger for the detonation. For various values of white dwarf mass and initial magnetic field strength this allows a range of supernova luminosities above those expected from single degenerate Chandrasekhar mass WD detonations to be achieved from this mechanism alone.
