Observational constraints on hyperons in neutron stars

Benjamin D. Lackey, Mohit Nayyar, and Benjamin J. Owen
Phys. Rev. D 73, 024021 – Published 23 January 2006

Abstract

The possibility that neutron stars may contain substantial hyperon populations has important implications for neutron-star cooling and, through bulk viscosity, the viability of the r-modes of accreting neutron stars as sources of persistent gravitational waves. In conjunction with laboratory measurements of hypernuclei, astronomical observations were used by Glendenning and Moszkowski [Phys. Rev. Lett. 67, 2414 (1991)] to constrain the properties of hyperonic equations of state within the framework of relativistic mean-field theory. We revisit the problem, incorporating recent measurements of high neutron-star masses and a gravitational redshift. We find that only the stiffest of the relativistic hyperonic equations of state commonly used in the literature is compatible with the redshift. However, it is possible to construct stiffer equations of state within the same framework which produce the observed redshift while satisfying the experimental constraints on hypernuclei, and we do this. The stiffness parameter that most affects the redshift is not the incompressibility but rather the hyperon coupling. Nonrelativistic potential-based equations of state with hyperons are not constrained by the redshift, primarily due to a smaller stellar radius.

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  • Received 13 July 2005

DOI:https://doi.org/10.1103/PhysRevD.73.024021

©2006 American Physical Society

Authors & Affiliations

Benjamin D. Lackey, Mohit Nayyar, and Benjamin J. Owen

  • Center for Gravitational Wave Physics, Institute for Gravitational Physics and Geometry, Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA

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Issue

Vol. 73, Iss. 2 — 15 January 2006

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