Compact stars in R-squared gravity

GARCÍA, F.; TEPPA-PANIA, F.A.; M. ORELLANA; G.E.ROMERO

Mar del Plata

Congreso; 55 Reunión anual de la Asociación Argentina de Astronomía; 2012

Asociación Argentina de Astronomía

Recent progress in testing certain modified-gravity theories has been achieved by the the study of the structure of compact objects like Black Holes and Neutron Stars (NSs). These objects are expected to display differences in different theories of gravity. In particular, it is possible that the squared-gravity generalization of the Lagrangian density, given by the function f(R); R+alpha R^2, may yield acceptable models for heavier NSs than in General Relativity (GR). Hence, high-precision measurements of the masses and radii of NSs can be used to constrain free parameters of these theories. The differences among alternative gravity theories must be enhanced in the strong gravitational regime. In such regime, perturbative methods are required to approach solutions, because of the complexity of the field equations. In this work, we solve the perturbative equations to calculate the structure of both NSs and Quark Stars, focusing on the behaviour of their interior profiles, compared to those obtained with GR. We find that these profiles depend on the choice of the Equation of State, in correlation with high-order derivatives. Finally, we discuss a possible method to test the general validity of the perturbative approach in this regime.