The interaction between hyperons and the surface gravitational redshift of proto neutron star PSR J0740+6620

An effect of the contributions from sigma;^* and phiv; mesons on the surface gravitational redshift of PNS PSR J0740+6620 is studied with relativistic mean field theory in consideration of a baryon octet. We find that the energy density egr; increases relative to the same pressure as the contributions from sigma;^* and phiv; mesons are taken into account. Relative to the same central energy density, the radius of the PNS increases while the mass , the mass radius ratio /R and the surface gravitational redshift of the PNS decrease, taking into account the contributions from sigma;^* and phiv; mesons. Under the constraint of mass =2.08 M_⊙, considering the contributions from sigma;^* and phiv; mesons, for the PNS PSR J0740+6620, the radius decreases by about -0.08%, the central energy density increases by about 0.89%, the central pressure increased by about 0.76%, the mass radius ratio increases by about 0.08%, and the surface gravitational redshift increases by about 0.17% from =0.31663 to =0.31718.