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Nucleosynthesis in neutron-rich ejecta from quark-novae

Prashanth Jaikumar·Bradley S. Meyer·Kaori Otsuki·Rachid Ouyed
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Abstract

We explore heavy-element nucleosynthesis by rapid neutron capture (r-process) in the decompressing ejecta from the surface of a neutron star. The decompression is triggered by a violent phase transition to strange quark matter (quark-nova scenario). The presence of neutron-rich large Z nuclei (40,95) < (Z,A) < (70,177), the large neutron-to-seed ratio, and the low electron fraction Ye ~ 0.03 in the decompressing ejecta present favorable conditions for the r-process. We perform network calculations that are adapted to the quark-nova conditions, and which mimic usual (n-gamma) equilibrium r-process calculations during the initially cold decompression phase. They match to dynamical r-process calculations at densities below neutron drip (4.10^11 g cm-3). We present results for the final element abundance distribution with and without heating from nuclear reactions, and compare to the solar abundance pattern of r-process elements. We highlight the distinguishing features of quark-novae by contrasting it with conventional nucleosynthetic sites such as type II supernovae and neutron star mergers, especially in the context of heavy-element compositions of extremely metal-deficient stars.

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Prashanth Jaikumar, Bradley S. Meyer, Kaori Otsuki, Rachid Ouyed. 2007-08-20. Nucleosynthesis in neutron-rich ejecta from quark-novae. https://doi.org/10.1051/0004-6361%3A20066593

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