p-process nucleosynthesis inside supernova-driven supercritical accretion disks

We investigate p-process nucleosynthesis in a supercritical accretion disk around a compact object of 1.4 M_⊙, using the self-similar solution of an optically thick advection-dominated flow. Supercritical accretion is expected to occur in a supernova with fallback material accreting onto a newborn compact object. It is found that an appreciable number of p-nuclei are synthesized via the p-process in supernova-driven supercritical accretion disks (SSADs) when the accretion rate m^̇ = M ^̇c²/(16L_Edd) > 10⁵, where L_Edd is the Eddington luminosity. Abundance profiles of p-nuclei ejected from SSADs have features similar to those of the oxygen/ neon layers in Type II supernovae when the abundance of the fallback gas far from the compact object is that of the oxygen/neon layers in the progenitor. The overall abundance profile is in agreement with that of the solar system. Some p-nuclei, such as Mo, Ru, Sn, and La, are underproduced in the SSADs as in Type II supernovae. If the fallback gas is mixed with a small fraction of protons through Rayleigh-Taylor instability during the explosion, significant amounts of ⁹²Mo are produced inside the SSADs. Isotopes ⁹⁶Ru and ¹³⁸La are also produced when the fallback gas contains abundant protons, although the overall abundance profile of p-nuclei is rather different from that of the solar system. The p-process nucleosynthesis in SSADs contributes to the chemical evolution of p-nuclei, in particular ⁹²Mo, if several percent of the fallback matter are ejected via jets and/or winds.