Properties Of Rapid Rotating Hybrid Stars With Non-newtonian Gravity

Equation of state (EOS) is an important input in theoretical research of neutron stars. Byinputting the data of EOS to TOV equation, we can get the global properties, such as the mass,the radius, and the internal structure of neutron stars like the distribution of density andpressure. Different EOS will correspond to different macroscopic characteristics of neutronstars. Measurements of the mass and radius of neutron stars can constrain the EOS ofsuper-dense matter, which play a very important role in the basic physical theory, especially,the observation of massive neutron star, such as the recently observed PSR J1614-2230(witha mass of1.97±0.04M⊙measured by using the general relativistic Shapiro delay, providesa more strict constraint on the EOS. Under the framework of classical theory, the mass of PSRJ1614-2230will exclude all the softer EOS. But the existence of quark matter, hyperons andmeson condensation will soften the equation of state soft, for example, the hybrid stars, whichcontain a quark core, have a soft EOS. Meanwhile, the terrestrial nuclear laboratory date alsosupports that dense asymmetric nuclear matter has a softer EOS.Can the observation of massive neutron star really rule out the softer equation of state?Our answer is No. It is unlikely that the massive neutron stars alone can rule out any EOSbefore gravity is well understood. In small-scale, the gravity has a serious deviation fromNewtonian gravity, which provides an effective mechanism to let the massive neutron starsupported by the soft EOS. In this paper, the structure and properties of rapid rotating hybridstars with by considering the non-Newtonian gravity (described by the Yukawa contribution)are investigated. The properties include the mass-radius relationship, the Kepler rotatingfrequency, the moment of inertia, the gravitational redshift and the ratio of the rotationalenergy to the gravitational energy. It is shown that at the Kepler frequency, the maximumstellar mass increases up to about20%compared with the static models at the same centraldensity. It is also shown that for a rapid rotating hybrid star, there is a clear rotating effect onthe bulk properties, such as the mass-radius relationship, the moment of inertia, the ratio ofthe rotational energy and gravitational energy, but a faint effect on the polar gravitationalredshift.