Nucleosynthesis inside supernova-driven supercritical accretion disks

We have investigated 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 new-born compact object. It has been found that appreciable nuclear reactions take place even for a reasonable value of the viscosity parameter, α_vis ≃ 0.01, when the accretion rate ṁ = Ṁc²/(16L_Edd) > 10⁵, where L_Edd is the Eddington luminosity. If ṁ ≥ 4 × 10⁶, all heavy elements are destroyed to ⁴He through photodisintegrations at the inner part of the disk. Even ⁴He is also disintegrated to protons and neutrons near the inner edge when ṁ ≥ 2 × 10⁷. If the fallback matter of the supernova explosion has the composition of a helium-rich layer of the progenitor, a considerable amount of ⁴⁴Ti could be ejected via a jet from the disk.