Talk detail

Participant	Zanchin, Vilson
Institution	Universidade Federal do ABC - Avenida dos Estados, 5001 - Santo Andre - Sao Paulo - Brazil

Session	AT3	Accepted		Order	Time
Talk	Oral abstract	Title	Charged polytropic stars and quasiblack holes
Co-authors
Abstract	We explore some extremal limits of charged spheres considering a charged perfect fluid with a polytropic equation of state. The study is performed by solving the Tolman-Oppenheimer-Volkoff (TOV) equation, which describe the hydrostatic equilibrium, for a charged perfect fluid. The numerical results showing the dependence of the star structure on the particular equation of state and for different charge densities are given. The charge density is chosen to be proportional to the energy density. Besides reviewing the structure of charged stars, our main interest is verifying if very compact objects such as quasiblack holes can be modeled by a polytropic fluid. We first verify the Buchdahl limit for uncharged polytropic spheres, which happens in the limit of very high polytropic indexes. As in the uncharged case, it is found that the extremal limit, i.e., the quasiblack hole limit, is found just when considering very high polytropic indexes. We also study other physical properties of the charge spheres, such as the dependence of the total mass, total charge, radius and of the sound speed on the polytropic index.