Seminari di gruppo IV

Gravitational collapse: structure formation and scalar fields

by Dr Ilia Musco (University of Oslo)

0m04 (Dipartimento di Fisica)


Dipartimento di Fisica

Gravitational collapse is the main mechanism leading to structure formation of different types in the Universe. The phenomenology depends on the characteristics of the matter involved, with there being a crucial distinction between zero and non-zero rest-mass particles. In the first case, described by a barotropic equation of state with the pressure depending on only one free parameter (the energy density), the collapse gives rise to critical collapse phenomenology and can lead only to either formation of a black hole or eventual dispersal back into the surrounding medium. In the second case instead, characterized by an equation of state with at least two free parameters (introducing a characteristic scale into the problem), the collapse could also give rise to a virialized condensed structure different from a black hole. In this talk I will investigate this mechanism, showing various numerical examples obtained with spherical collapse calculations. Finally I will present some recent results on Dark Energy models, in the context of the Chameleon screening mechanism, obtained by solving the TOV + KG equations for polytropic stars.