Coulomb corrections to the equation of state of nuclear statistical equilibrium matter: implications for SNIa nucleosynthesis and the accretion-induced collapse of white dwarfs

Coulomb corrections to the equation of state of degenerate matter are usually neglected in high-temperature regimes, owing to the inverse dependence of the plasma coupling constant, G, on temperature. However, nuclear statistical equilibrium matter is characterized by a large abundance by mass of large-Z (iron group) nuclei. It is found that Coulomb corrections to the ion ideal gas equation of state of matter in nuclear statistical equilibrium are important at temperatures T & 5±10 10 K and densities r * 10 g cm. At a temperature T ˆ 8:5 10 K and a density r ˆ 8 10 g cm, the neutronization rate is larger by *28 per cent when Coulomb corrections are included. However, the conductive velocity of a thermonuclear deflagration wave in C±O drops by ,16 per cent when Coulomb corrections to the heat capacity are taken into account. The implications for SNIa models and nucleosynthesis, and also for the accretion-induced collapse of white dwarfs, are discussed. Particularly relevant is the result that the minimum density for collapse of a white dwarf to a neutron star is shifted down to 5:5±6 10 g cm, a value substantially lower than