The Hyperons in the Massive Neutron Star PSR J0348+0432

Abstract

Whether the massive neutron star PSR J0348+0432 can become a hyperon star is examined in the framework of the relativistic mean field theory by adjusting the hyperon coupling constants. It is found that at the central baryon number density of the massive neutron star PSR J0348+0432, the relative particle number density of hyperons is smaller than those of neutrons and so it can not change into a hyperon star. In its center, it is mainly composed of $\Lambda$, $\Xi^{-}$ and a few $\Xi^{0}$. We also found that for the neutron star with a maximum mass of 1.4 M$_{\odot}$, it can change into a hyperon star and the hyperon star transition density is 0.668 fm$^{-3}$, at which the hyperons are only composed of $\Lambda$. At its center, the hyperons are also only composed of $\Lambda$ and the ratio of the hyperons is a little larger than that of the neutrons. This illustrates that the NS1.4M$_{\odot}$ has just changed into a hyperon star.