DECONFINEMENT PHASE TRANSITION IN RELATIVISTIC NEUTRON STAR MERGERS

Abstract

We consider the influence of the deconfinement phase transition on gravitational waves (GW) emitted in a binary neutron star merger. We perform 3D hydrody- namic simulations based on the conformally flat approximation to general rela- tivity and the GW signal extracted up to quadrupole order. We vary the initial constituent masses of the binary by use of physically-motivated equations of state (EoS) at zero temperature in two ways - allowing stellar matter to undergo or not the hadron-quark phase transition. It has been shown, that for a binary system close to the innermost stable circular orbit (ISCO) with constituent grav- itational masses larger than M∞ 1.5 Mthe EoS dependent effects in GW signals begin to play a role. The difference in the gravitational wave frequency at the ISCO is to up to 10% for the maximal allowed mass given by the used model EsoS - M∞ 1.75 M� . We determine the characteristic GW frequen- cies of the merger remnants, where the pronounced implications of quark matter show up as a phase difference in the post-merger GW signal, for stellar matter undergoing or not the deconfinement phase transition and collapse does not take place immediately after merger.