Coulomb corrections to the equation of state of nuclear statistical equilibrium matter: implications for SNIa nucleosynthesis and the accretion-induced collapse of white dwarfs |
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| Authors: | E Bravo D García-Senz |
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| Institution: | Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Av Diagonal 647, 08028 Barcelona, Spain; Institut d'Estudis Espacials de Catalunya, Ed. Nexus 104, Gran Capità2–4, 08034 Barcelona, Spain |
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| Abstract: | 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, Γ, 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 ?5–10×109 K and densities ρ ?108 g cm?3. At a temperature T =8.5×109 K and a density ρ =8×109 g cm?3, 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 5.5–6×109 g cm?3, a value substantially lower than previously thought. |
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| Keywords: | equation of state nuclear reactions nucleosynthesis abundances stars: neutron supernovae: general white dwarfs |
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