Occurrence of hyperon superfluidity in neutron star cores

Nov, 2005
25 pages
Published in:
  • Prog.Theor.Phys. 115 (2006) 355-379
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Abstract:
Superfluidity of Λ\Lambda and Σ\Sigma^- admixed in neutron star (NS) cores is investigated realistically for hyperon (YY)-mixed NS models obtained using a GG-matrix-based effective interaction approach. Numerical results for the equation of state (EOS) with the mixing ratios of the respective components and the hyperon energy gaps including the temperature dependence are presented. These are meant to serve as physical inputs for YY-cooling calculations of NSs. By paying attention to the uncertainties of the EOS and the YYYY interactions, it is shown that both Λ\Lambda and Σ\Sigma^- are superfluid as soon as they appear although the magnitude of the critical temperature and the density region where superfluidity exists depend considerably on the YYYY pairing potential. Considering momentum triangle condition and the occurrence of superfluidity, it is found that a so-called `` hyperon cooling\rq\rq~(neutrino-emission from direct Urca process including YY) combined with YY-superfluidity may be able to account for observations of the colder class of NSs. It is remarked that Λ\Lambda-hyperons play a decisive role in the hyperon cooling scenario. Some comments are given regarding the consequences of the less attractive ΛΛ\Lambda\Lambda interaction recently suggested by the `` NAGARA event\rq\rq~ΛΛ6^6_{\Lambda\Lambda}He.
  • neutron star
  • Lambda: superfluid
  • Sigma-: superfluid
  • energy: gap
  • temperature dependence
  • hyperon hyperon: interaction
  • hyperon hyperon: potential
  • Urca process
  • neutrino: emission
  • Lambda: hypernucleus