Constraining hadron-quark phase transition parameters within the quark-mean-field model using multimessenger observations of neutron stars

Zhiqiang Miao, Ang Li, Zhenyu Zhu, Sophia Han.


We extend the quark mean-field (QMF) model for nuclear matter and study the possible presence of quark matter inside the cores of neutron stars. A sharp first-order hadron-quark phase transition is implemented combining the QMF for the hadronic phase with “constant-speed-of-sound” parametrization for the high-density quark phase. The interplay of the nuclear symmetry energy slope parameter, L, and the dimensionless phase transition parameters (the transition density n_{\rm trans}/n_0, the transition strength \Delta\varepsilon/\varepsilon_{\rm trans}, and the sound speed squared in quark matter c^2_{\rm QM}) are then systematically explored for the hybrid star proprieties, especially the maximum mass Mmax and the radius and the tidal deformability of a typical 1.4M star. We show the strong correlation between the symmetry energy slope L and the typical stellar radius R1.4, similar to that previously found for neutron stars without a phase transition. With the inclusion of phase transition, we obtain robust limits on the maximum mass (M_{\rm max}< 3.6 \,M_{\odot}) and the radius of 1.4M stars (R_{1.4}\gtrsim 9.6~\rm km), and we find that a too-weak (\Delta\varepsilon/\varepsilon_{\rm trans}\lesssim 0.2) phase transition taking place at low densities \lesssim 1.3-1.5 \, n_0 is strongly disfavored. We also demonstrate that future measurements of the radius and tidal deformability of ∼1.4M stars, as well as the mass measurement of very massive pulsars, can help reveal the presence and amount of quark matter in compact objects.

Associated Fellows