Neutron stars with small radii-the role of Δ resonances

Abstract

Recent neutron star observations suggest that the masses and radii of neutron stars may be smaller than previously considered, which would disfavor a purely nucleonic equation of state (EoS). In our model, we use a flavor SU(3) sigma model that includes Δ resonances and hyperons in the EoS. We find that if the coupling of the Δ resonances to the vector mesons is slightly smaller than that of the nucleons, we can reproduce both the measured mass-radius relationship and the extrapolated EoS. © 2010 The American Astronomical Society. All rights reserved.