The pulsar PSR J0348-0432 and strange stars

Abstract

The possible constraints on the equation of state for superdense baryonic matter to which an accurate measurement of the mass for the binary radio pulsar PSR J0348-0432 (M/M⊙ = 2.01 ± 0.04) leads have been determined. We use the bag model for strange quark matter (SQM), where the transition to the SQM state occurs at an energy density that does not exceed twice the density in atomic nuclei. Therefore, on the curve of massM for equilibrium superdense configurations versus central energy density ρ c (the M(ρ c ) curve), low-mass neutron stars and configurations consisting of SQM form one family in central density. The sets of three phenomenological bag constants (the vacuum pressure B, the quarkgluon interaction constant α c , and the strange quark mass ms) have been determined. Using them in the equation of state for SQM leads to maximum massesM max of equilibrium configurations greater than 2.01M ⊙ (M max ≥ 2.01M ⊙). For such equations of state for configurations withM max and M/M ⊙ = 2.01, we have calculated themass, the radius, the total number of baryons, and the redshift fromthe stellar surface as a function of the central energy density ρ c . It turns out that if we restrict the quark-gluon interaction constant α c , in terms of which the expansion is performed in the perturbation theory when determining the thermodynamic potentials Ω i , i = u, d, and s, to α c < 0.6, then, according to the derived equations of state, the above-mentioned pulsar can be a possible candidate for strange stars.