Nucleosynthesis of heavy elements in gamma ray bursts

TL;DR

This paper investigates how heavy elements are formed in gamma ray burst engines, focusing on nucleosynthesis in accretion disks around black holes, with implications for observed afterglow spectra.

Contribution

It presents a detailed analysis of nucleosynthesis processes in GRB engines, highlighting conditions for heavy element formation in accretion flows.

Findings

Heavy nuclei form at 150-250 gravitational radii from the black hole.

Neutron-rich plasma conditions are prevalent in the outflows.

Results suggest observable signatures in GRB afterglow spectra.

Abstract

The ultrarelativistic jets responsible for prompt and afterglow emission in gamma ray bursts are presumably driven by a central engine that consists of a dense accretion disk around a spinning black hole. We consider such engine, composed of free nucleons, electron-positron pairs, Helium nuclei, and cooled by neutrino emission. A significant number density of neutrons in the disk provide conditions for neutron rich plasma in the outflows and jets. Heavy nuclei are also formed in the accretion flow, at the distances 150-250 gravitational radii from the black hole. We study the process of nucleosynthesis in the GRB engine, depending on its physical properties. Our results may have important observational implications for the jet deceleration process and heavy elements observed in the spectra of GRB afterglows.