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Physical Review D 81 (2010) 124051
Relativistic stars in f(R) and scalar-tensor theories
E. Babichev1, D. Langlois2

We study relativistic stars in the context of scalar-tensor theories of gravity that try to account for the observed cosmic acceleration and satisfy the local gravity constraints via the chameleon mechanism. More specifically, we consider two types of models: scalar-tensor theories with an inverse power law potential and f(R) theories. Using a relaxation algorithm, we construct numerically static relativistic stars, both for constant energy density configurations and for a polytropic equation of state. We can reach a gravitational potential up to Φ˜0.3 at the surface of the star, even in f(R) theories with an "unprotected" curvature singularity. However, we find static configurations only if the pressure does not exceed one third of the energy density, except possibly in a limited region of the star (otherwise, one expects tachyonic instabilities to develop). This constraint is satisfied by realistic equations of state for neutron stars.
1 :  LPT - Laboratoire de Physique Théorique d'Orsay [Orsay]
2 :  APC - UMR 7164 - AstroParticule et Cosmologie
Physique/Relativité Générale et Cosmologie Quantique

Physique/Physique des Hautes Energies - Théorie
Modified theories of gravity – Relativistic stars: structure – stability – and oscillations – Dark energy
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