Speaker
Description
At extremely high densities, QCD predicts the possible liberation of quark degrees of freedom and the formation of quark matter. The cores of neutron stars (NS) may accommodate such high-density matter. Whether the quark matter exists inside NSs is still an open question. If the quark matter exists, then there should be the imprint of the hadron-to-quark phase transition in the equation of state (EoS). We expect that gravitational waves from the binary NS merger can further constrain the EoS with the help of future third-generation detectors.
In this talk, we show that gravitational waves in the post-merger phase can distinguish the theory scenarios with and without a hadron-to-quark phase transition. Instead of adopting specific phenomenological EoS as studied previously, we compile reliable EoS constraints from the ab-initio QCD calculations. We demonstrate that early collapse to a black hole after the NS merger signifies softening of the EoS associated with quark matter even without a strong first-order transition. We also explain that the electromagnetic counterparts may further constrain the nature of the hadron-to-quark phase transition; we need substantial mass ejection to energize the observed luminosity of the associated kilonova.
