Speaker: 

Manuel Malheiro  

Departamento de Física, Instituto Tecnológico de Aeronáutica (ITA), Sao Paulo

Abstract:

We analyze wheter polytropic equations of state can be a good  approximation for neutron stars. Dividing the matter in the star interior in different regions that can be well reproduced by different polytropics and imposing the continuity of the pressure and energy ensity among the regions, we obtain the corresponding neutron star mass-radius diagram. A comparison with the results obtained with the polytropic approximation and the exact relativistic mean field quation of state (EOS) is shown for two compositions of the hadronic matter. We conclude that with more than one polytropic EOS, it is ossible to obtain a good fit to neutron stars only if the pressure is written as a power law in the energy density (or mass density) and not in the baryonic density (the usual polytropic approximation). We also ound a correlation between the sound velocity and incompressibility at the star center with its mass.

Place:

Physics Department Meeting Room, 2nd floor