2006/08/25 by Shinya Wanajo · 25 citations
Physics and Astronomy · #Anisotropy #Annihilation #Astrophysics and Cosmic Phenomena #Cosmic neutrino background #Dark Matter and Cosmic Phenomena #Measurements of neutrino speed #Neutrino #Neutrino Physics Research #Neutrino oscillation #Nucleosynthesis #Solar neutrino #astro-ph
paper · pdf · doi:10.1086/508568
published in The Astrophysical Journal 650(1), L79-L82 (IOP Publishing) · 8 pages, 3 figures, accepted for publication in ApJ Letters
arxiv created 2006/08/25 · openalex publication_date 2006/09/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The astrophysical origin of the r -process nuclei is still unknown. Even the most promising scenario, the neutrino-driven winds from a nascent neutron star, encounters severe difficulties in obtaining the requisite entropy and short dynamic timescale for the r -process. In this study, the effect of anisotropy in neutrino emission from a proto-neutron star surface is examined with semianalytic neutrino-driven wind models. The increase of neutrino number density in the wind owing to the anisotropy is modeled schematically by enhancing the effective neutrino luminosity. It is shown that the neutrino heating rate from neutrino-antineutrino pair annihilation into electron-positron pairs can significantly increase owing to the anisotropy and can play a dominant role in the heating of wind material. A factor of 5 increase in the effective neutrino luminosity results in a 50% higher entropy and a factor of 10 shorter dynamic timescale owing to this enhanced neutrino heating. The nucleosynthesis calculations show that this change is enough for the robust r -process, producing the third abundance peak ( A = 195) and beyond. Future multidimensional studies with accurate neutrino transport will be needed if such anisotropy relevant to the current scenario (more than a factor of a few) is realized during the wind phase (~1-10 s).