19-23 October 2020
Europe/Prague timezone
Please, give us your feedback in the Survey

Dynamical instability of polytropes in spacetimes with a cosmological constant

19 Oct 2020, 13:15
Online talk Monday Afternoon


Camilo Posada (Silesian University in Opava)


The dynamical instability of relativistic polytropic spheres, embedded in a spacetime with a repulsive cosmological constant, is studied in the framework of general relativity. We apply the methods used in our preceding paper to study the trapping polytropic spheres with Λ=0, namely, the critical point method and the infinitesimal and adiabatic radial perturbations method developed by Chandrasekhar. We compute numerically the critical adiabatic index, as a function of the parameter σ=pc/(ρcc2), for several values of the cosmological parameter λ giving the ratio of the vacuum energy density to the central energy density of the polytrope. We also determine the critical values for the parameter σcr, for the onset of instability, by using both approaches. We found that for large values of the parameter λ, the differences between the values of σcr calculated by the critical point method differ from those obtained via the radial perturbations method. Our results, given by both applied methods, indicate that large values of the cosmological parameter λ have relevant effects on the dynamical stability of the polytropic configurations.

Primary author

Camilo Posada (Silesian University in Opava)


Dr Jan Hladík (Institute of Physics in Opava, Silesian University) Prof. Zdeněk Stuchlík (Silesian University in Opava, Czech Republic)

Presentation Materials