Nucleosynthesis in neutron-rich ejecta from quark-novae
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-γ) equilibrium r-process calculations during the initially cold decompression phase. They match to dynamical r-process calculations at densities below neutron drip (4 × 1011 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.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- August 2007
- DOI:
- 10.1051/0004-6361:20066593
- arXiv:
- arXiv:nucl-th/0610013
- Bibcode:
- 2007A&A...471..227J
- Keywords:
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- dense matter;
- nuclear reactions;
- nucleosynthesis;
- abundances;
- stars: neutron;
- Nuclear Theory;
- Astrophysics
- E-Print:
- journal version