Nucleosynthesis of r-process elements by jittering jets in core-collapse supernovae

Abstract

We calculate the nucleosynthesis inside the hot bubble formed in the jittering-jets model for core-collapse supernova explosions, and find the formation of several times 10 -4M ⊙ r-process elements. In the jittering-jets model, fast jets launched from a stochastic accretion disc around the newly formed neutron star are shocked at several thousand km, and form hot high-pressure bubbles. These bubbles merge to form a large bubble that explodes the star. In this study, we assume a spherically symmetric homogenous bubble, and follow its evolution for about 1 s during which nuclear reactions take place. The jets last for about 1 s, their velocity v j= 0.5c, and their total energy is ∼10 51erg. We use jets' neutron enrichment independent of time, and follow the nuclear reactions to the formation of seed nuclei up to Z≤ 50, on which more neutrons will be absorbed to form r-process elements. Based on the mass of the seed nuclei, we find the r-process element mass in our idealized model to be several times 10 -4M ⊙, which is slightly larger than the value deduced from observations. More realistic calculations that relax the assumptions of a homogenous bubble and constant-power jets' composition might lead to agreement with observations. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.