Self-gravity Correction to the Chandrasekhar Limiting Mass of White Dwarfs

Abstract

While computing the Fermi degeneracy pressure of electrons in a white dwarf star within the framework of hydrostatic equilibrium, we depart from the extant practice of treating the electrons as a free fermion gas, by including the effect of the star's self-gravity as an effective gravitational potential. By the star's self gravity, we mean the gravitational field due to the star itself, resulting from the mass of its constituent atoms, the mass of the atom being effectively the mass of the proton. Modifying the free particle Hamiltonian with this effective potential, we employ first order quantum mechanical perturbation theory to compute the degeneracy pressure, in order to study the effect of inclusion of this self-gravity of the star on the Chandrasekhar limiting mass. The final effect is found to be non-trivial, but perhaps a shade too small to alter any major observational result.

8 Pages, No figures, Latex, typo in surname of first author corrected to `Ray' from `Roy; minor other typos corrected; concluding section slightly expanded with additional remarks; a few references added; no major changes in rest of text or in results