Effects of free parameterized TOV equations on properties of neutron stars with hyperons

Abstract

In view of the crucial role of the structure in neutron star (NS) research, parameterized TOV (PTOV) equations are used to calculate the static NS sequence with five parameters including [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], which represent the five factors that impact the NS structure. In order to promote the efficiency in the combination of astronomical observations and the theory, we investigate the meticulous influences of the five factors on NS structure with various hyperons in this work. Results show that the maximum masses of NSs are reduced with the free parameters, respectively, whereas the variation trend of corresponding radii is wavy in some cases. Especially, when hyperons are included, the macroscopic properties of NSs, except redshift, are relatively smaller than those in conventional NS matter. The effects on conventional NSs and hyperonic NSs are quite different in the high NS mass area but diminish when the stellar mass is lower than approximately 1.5 times solar mass. Finally, comparing with observations, we predict constraints on the free parameters.