Light Element Synthesis in High Entropy Relativistic Flows Associated with Gamma Ray Bursts.pdf

Light Element Synthesis in High Entropy Relativistic Flows Associated With Gamma Ray Bursts Jason Pruet Lawrence Livermore National Laboratory, L-414, P.O. Box 808, Livermore, CA 94551 2 0 Shannon Guiles and George M. Fuller 0 2 Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319 y a M ABSTRACT 3 1 We calculate and discuss the light element freeze-out nucleosynthesis in high v 6 entropy winds and fireballs for broad ranges of entropy-per-baryon, dynamic 5 timescales characterizing relativistic expansion, and neutron-to-proton ratios. 0 5 With conditions characteristic of Gamma Ray Bursts (GRBs) we find that deu- 0 terium production can be prodigious, with final abundance values 2H/H 2%, 2 0 depending on the fireball isospin, late time dynamics, and the effects of neutron / h decoupling-induced high energy non-thermal nuclear reactions. This implies that p - there potentially could be detectable local enhancements in the deuterium abun- o dance associated with GRB events. r t s a : Subject headings: gamma rays:bursts—nucleosynthesis—stars:neutron v i X r a 1. Introduction In this paper we show that the high entropy relativistic flows thought to accompany catastrophic stellar endpoint events like binary neutron star mergers (Eichler et al. 1989) and collapsars (MacFadyen Woosley 1999) may be a source of interesting light element synthesis. In particular, we find that under the right circumstances a significant fractio