Strangeness content of neutron stars with strong Σ--hyperon repulsion

• Published in: Astronomische Nachrichten 2014-08, Vol.335 (6-7), p.739-744
• Main Authors: Razeira, M., Mesquita, A., Vasconcellos, C.A.Z., Ruffini, R., Rueda, J.A., Gomes, R.O.
• Format: Article
• Language: English
• Subjects: dense matter; equation of state; stars: neutron
• ISSN: 0004-6337; 1521-3994
• DOI: 10.1002/asna.201412102

A new constraint on the equation of state and composition of the matter on neutron stars has been provided by the measurement of the mass 2.01 ± 0.04 M⊙ for PSR J0348 +0432. In this contribution we investigate the role of many‐body correlations in the maximum mass of neutron stars using the effective relativistic QHD‐model with parameterized couplings. The complete expression of our QHD interaction Lagrangian exhausts the whole fundamental baryon octet (n, p, Σ–, Σ0, Σ+, Λ, Ξ–, Ξ0) and includes many‐body forces simulated by nonlinear self‐couplings and meson‐meson interaction terms involving scalar‐isoscalar (σ, σ*), vector‐isoscalar (ω, ϕ), vector‐isovector (∼), and scalar‐isovector (δ). We study the behavior of the asymmetry parameter, which describes the relative neutron excess in the system as well as the behavior of the strangeness asymmetry parameter, which specifies the strangeness content in the system and is strictly connected with the appearance of a particular hyperon species in the extreme case where the Σ– experiences such a strong repulsion that it does not appear at all in nuclear matter. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)