Antikaons and higher order couplings in the relativistic mean-field study of neutron stars

Abstract

We investigate the role of higher order couplings, along with the condensation of antikaons (K− and ), on the properties of neutron stars (NS). We employ extended versions of the relativistic mean-field model, in which kaon–nucleon and nucleon–nucleon interactions are taken on the same footing. We find that the onset of condensation of K− and highly depends not only on the strength of optical potential but also on the new couplings. The presence of antikaons leads to a softer equation of state and makes the neutron star core symmetric and lepton-deficient. We show that these effects strongly influence the mass–radius relation as well as the composition of the neutron star. We also show that the recently observed 1.97±.04 solar mass NS can be explained in three ways: (i) a stiffer EoS with both antikaons, (ii) a relatively soft EoS with K− and (iii) a softer EoS without antikaons.