2007/03/31 by Hylke Koers, Hylke B. J. Koers, Dimitrios Giannios
Physics and Astronomy · #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1051/0004-6361:20077560
published as Astron.Astrophys.471:395-408,2007 · 15 pages, 6 figures, accepted for publication by A&A. Minor revisions: added references and one extra figure
openalex publication_date 2007/06/18 · arxiv created 2007/09/07 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/01
We consider gamma-ray burst outflows with a substantial neutron component that are either dominated by thermal energy (fireballs) or by magnetic energy. In the latter case, we focus on the recently introduced “AC” model which relies on magnetic reconnection to accelerate the flow and power the prompt emission. For both the fireball and the AC model, we investigate the dynamical importance of neutrons on the outflow. We study particle creation in inelastic neutron-proton collisions and find that in both models the resulting neutrino emission is too weak to be detectable. The inelastic collisions also produce γ-rays, which create pairs in interactions with soft photons carried with the flow. In magnetically driven outflows, the energy of these pairs is radiated away as synchrotron emission. The bulk of the emission takes place at a few hundred keV, which makes it difficult to disentangle this signal from the prompt emission. In fireballs, however, pair cascading leads to the emission of γ-rays with observer energy in the range of 2–20 GeV and a fluence well above the GLAST threshold. Therefore this emission can be a useful diagnostic of the nature of the outflow.