Universal behavior of a compact star based upon the gravitational binding energy

Abstract

Similar to the compactness parameter ($\beta=M/R$), the gravitational binding energy (GBE) is also a characteristic parameter which can reflect the internal structure of a neutron star and thus can be used to expressing the universal relations. Scaling by the stellar mass, this investigation demonstrates a perfect universal relation between the GBE and the moment of inertia, where both of the normal neutron stars and the quark stars satisfy the same universal relation. Moreover, a fine empirical relation between the GBE and the tidal deformability is proposed, where the difference of the relations can be used to distinguish wether a pulsar is a normal neutron star or a quark star if the stellar mass and the tidal deformability can be observed or estimated rather accurately. These universal relations provide a potential way to estimate the GBE if the stellar mass and the moment of inertia/the tidal deformability are precisely measured.