Relativistic Tidal Deformations of Neutron Stars with Hybrid Equations of States

An exploration of how the tidal properties measured in gravitational waves (GWs) from coalescing neutron stars can be utilized to constrain the elusive neutron star (NS) equation of state (EoS) was conducted. Realistic EoS models that featured phase transitions to quark matter, governed by the vector interaction enhanced BAG (vBAG) model, were employed to simulate behavior that is more consistent with quantum chromodynamics (QCD) calculations. From these models, relations between the mass-weighted tidal deformability, Λeff, and the binary mass ratio, q = M2/M1, were analyzed to determine if a given EoS, meets the criterion determined by the GW170817 signal of 400 ≤ Λeff ≤ 800 for 0.7 ≤ q ≤ 1.0. By analyzing the tidal deformability of a single star, Λ, under the condition that Λ(1.4Msolar) ≤ 800 and 2.01Msolar ≤ max(M) ≤ 2.16Msolar, constraints to the EoS of the strongly-interacting dense matter on the interiors of NSs can be placed. We find that nuclear models of EoS with Λ(1.4Msolar) > 800 cannot easily be ruled out because a transition to quark matter can occur, which would result in a more compact hybrid configuration--thus a lower Λ.