Thermal evolution of hybrid stars
PT-CERN Call 2020/2
Universidade de Coimbra
CFISUC - Centro de Fisica da Universidade de Coimbra
The compact astrophysical objects, i.e. neutron stars (NSs), hypothetical hybrid (HSs) and quark stars (QSs), are the most dense physical objects accessible by direct observations. Despite the flourishing of astrophysical observations, the particle composition of the interior of compact stars is still very poorly known. Moreover, the physical processes inside hypothetical objects like HSs and QSs, for which is expected that matter goes through a phase transition from nuclear matter to a plasma of strongly interacting quarks, are also very poorly understood. Particularly, this limitation comes from the fact that QCD and its lattice formulation have very limited applicability at large baryonic densities and as such does not allow to obtain a reliable equation of state (EoS). Detection of QS or HS can become another scientific breakthrough and prove the existence of quark matter, which is the main quest of largest research collaborations, such as ALICE at the Large Hadron Collider (LHC) in CERN. Compact stars cool down through a combination of thermal radiation from the surface and neutrino emission from the inner layers. Observational data on the surface temperature and the luminosity of stars provide valuable information about their internal composition, the EoS, the chemical abundances of the envelope and the degree, type and model of pairing of their constituent particles. Studying of the thermal evolution of compact objects with a quark core is the primary goal of the present research project. Existence of the quark-hadron phase transition, as well as other phase transitions to a denser phase of quark matter, will have an impact on the dynamics of the HS cooling. Their modeling can provide the community with an important opportunity to probe the existence and properties of phase transitions, as well as the EoS of strongly interacting matter at high densities. Another part of the PhD project will be dedicated to the study of the densest predicted phase on the QCD phase diagram, in which quarks can be paired between each other, and its impact on the thermal evolution of HSs. The thesis will be supervised by Constança Providência and Violetta Sagun, theoretical physicists, in the University of Coimbra.