Significantly super-Chandrasekhar limiting mass white dwarfs as progenitors for peculiar over-luminous type Ia supernovae

Abstract

Since 2012, we have initiated developing systematically the simplistic to rigorous models to prove that highly super-Chandrasekhar, as well as highly sub-Chandrasekhar, limiting mass white dwarfs are possible to exist. We show that the mass of highly magnetized or modified Einstein's gravity induced white dwarfs could be significantly super-Chandrasekhar and such white dwarfs could altogether have a different mass-limit. On the other hand, type Ia supernovae (SNeIa), a key to unravel the evolutionary history of the universe, are believed to be triggered in white dwarfs having mass close to the Chandrasekhar-limit. However, observations of several peculiar, over- and under-luminous SNeIa argue for exploding masses widely different from this limit. We argue that explosions of super-Chandrasekhar limiting mass white dwarfs result in over-luminous SNeIa. We arrive at this revelation, first by considering simplistic, spherical, Newtonian white dwarfs with constant magnetic fields. Then we relax the Newtonian assumption and consider the varying fields, however obtain similar results. Finally, we consider a full scale general relativistic magnetohydrodynamic description of white dwarfs allowing their self-consistent departure from a sphere to ellipsoid. Subsequently, we also explore the effects of modified Einstein's gravity. Our finding questions the uniqueness of the Chandrasekhar-limit. It further argues for a possible second standard candle, which has many far reaching implications.