Neutron stars at high rotational frequencies as laboratories of hot and dense nuclear matter

by Dr Polychronis Koliogiannis Koutmiridis (Aristotle University of Thessaloniki)


Neutron stars present the densest form of matter in the Universe by probing the strongly interacting matter at ultra-high densities and strong gravitational fields. The key quantity for their description is the nuclear equation of state of the fluid interior providing the neutron star structure. Explicitly, except for cold neutron star matter, finite temperature or entropy and rotational frequencies affect the dynamical processes of neutron stars. In particular, a set of zero and finite temperature equations of state is constructed and the role of non-thermal or thermal pressure is investigated. Furthermore, a systematic study on both non-rotating and rotating at the Kepler frequency neutron star properties is performed. Concurrent, a part is devoted to proto-neutron stars and the hot and rapidly rotating remnant of a binary neutron star merger, as they combine temperature and rotational effects. In each case, universal relations, constraints on the nuclear equation of state, and criteria for the final fate of compact objects are extracted. Additionally, the stability of neutron stars and its role in their internal structure is analysed. Finally, the theoretical tools from studying uniformly rotating neutron stars, containing cold or hot nuclear matter, along with the observation of isolated or binary neutron stars, will provide insightful constraints and shed light on the equation of state of dense nuclear matter.

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