The Nucleon Direct Urca Processes in a Cooling Neutron Star
XU Yan1, LIU Guang-Zhou2, LIU Cheng-Zhi1**, FAN Cun-Bo1, WANG Hong-Yan3, ZHU Ming-Feng2, ZHAO En-Guang4
1Changchun Observatory, National Astronomical Observatories, Chinese Academy of Sciences, Changchun 130117 2Center for Theoretical Physics, Jilin University, Changchun 130012 3College of Physics, Beihua University, Jilin 132013 4Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190
Abstract：In the relativistic mean field approximation, the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars. We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchanging δ meson on the nucleon direct Urca processes in neutron star matter. The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes, while it has only a little influence on the neutrino luminosity for a fixed neutron star whether δ mesons appear in a neutron star or not. However, the presence of δ mesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.
. [J]. 中国物理快报, 2013, 30(12): 129501-129501.
XU Yan, LIU Guang-Zhou, LIU Cheng-Zhi, FAN Cun-Bo, WANG Hong-Yan, ZHU Ming-Feng, ZHAO En-Guang. The Nucleon Direct Urca Processes in a Cooling Neutron Star. Chin. Phys. Lett., 2013, 30(12): 129501-129501.
2013, Vol. 30 
