Speaker
Description
We present a unified overview of our recent studies on hybrid neutron stars constrained by NICER observations of PSR J0740+6620 and PSR J0030+0451, and by the low-mass compact object in HESS J1731–347. The hadronic phase is modeled using relativistic mean-field (RMF) equations of state: multiple RMF parameterizations with different interaction schemes are employed for the NICER analysis to explore sensitivities to nuclear matter properties, while the IUFSU parameterization is adopted for the HESS J1731–347 study. The deconfinement transition to quark matter is described using the constant speed of sound (CSS) framework.
We study hybrid neutron star models constrained by NICER observations of PSR J0030+0451, PSR J0740+6620, and PSR J0952–0607 within the constant speed of sound (CSS) framework. Different surface temperature models for PSR J0030+0451 (scenarios A, B, and C) lead to distinct mass–radius estimates and corresponding constraints on the CSS parameters.
We further examine the formation of compact objects with small mass and radius and show that, HESS J1731–347 is compatible with a stable hybrid star undergoing early deconfinement with a sizable energy gap. We have also examined the effect of hadronic parameters such as effective mass, symmetry energy, and the slope of the symmetry energy at saturation densities on the formation of this compact object.
