The r-Process in Supersonic Neutrino-Driven Winds: The Roll of Wind Termination Shock - AstrophysicsReportar como inadecuado




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Abstract: Recent hydrodynamic studies of core-collapse supernovae imply that theneutrino-heated ejecta from a nascent neutron star develops to supersonicoutflows. These supersonic winds are influenced by the reverse shock from thepreceding supernova ejecta, forming the wind termination shock. We investigatethe effects of the termination shock in neutrino-driven winds and its roll onthe r-process. Supersonic outflows are calculated with a semi-analyticneutrino-driven wind model. Subsequent termination-shocked, subsonic outflowsare obtained by applying the Rankine-Hugoniot relations. We find a couple ofeffects that can be relevant for the r-process. First is the sudden slowdown ofthe temperature decrease by the wind termination. Second is the entropy jump bytermination-shock heating, up to several 100NAk. Nucleosynthesis calculationsin the obtained winds are performed to examine these effects on the r-process.We find that 1 the slowdown of the temperature decrease plays a decisive rollto determine the r-process abundance curves. This is due to the strongdependences of the nucleosynthetic path on the temperature during the r-processfreezeout phase. Our results suggest that only the termination-shocked windswith relatively small shock radii ~500km are relevant for the bulk of thesolar r-process abundances A~100-180. The heaviest part in the solarr-process curve A~180-200, however, can be reproduced both in shocked andunshocked winds. These results may help to constrain the mass range ofsupernova progenitors relevant for the r-process. We find, on the other hand,2 negligible roles of the entropy jump on the r-process. This is a consequencethat the sizable entropy increase takes place only at a large shock radius~10,000km where the r-process has already ceased.



Autor: Takami Kuroda, Shinya Wanajo, Ken'ichi Nomoto

Fuente: https://arxiv.org/







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