Anisotropic $e^+ e^-$ pressure due to the QED effect in strong magnetic fields and the application to the entropy production in neutrino-driven wind

Abstract

We study the equation of state of electron in strong magnetic fields which are greater than the critical value $B_c \simeq 4.4 \times 10^{13}$ Gauss. We find that such a strong magnetic field induces the anisotropic pressure of electron. We apply the result to the neutrino-driven wind in core-collapse supernovae and find that it can produce large entropy per baryon, $S \sim 400 k_B$. This mechanism might successfully account for the production of the heavy nuclei with mass numbers A = 80 -- 250 through the r-process nucleosynthesis.