Isotropic and anisotropic bouncing cosmologies in Palatini gravity

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.084015· OSTI ID:21432385

Barragan, Carlos ^[1]; Olmo, Gonzalo J ^[2]

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1. Departamento de Fisica Teorica, Universidad Autonoma de Madrid, 28049 Madrid (Spain)
2. Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain)

We study isotropic and anisotropic (Bianchi I) cosmologies in Palatini f(R) and f(R,R{sub {mu}{nu}R}{sup {mu}{nu}}) theories of gravity with a perfect fluid and consider the existence of nonsingular bouncing solutions in the early universe. We find that all f(R) models with isotropic bouncing solutions develop shear singularities in the anisotropic case. On the contrary, the simple quadratic model R+aR{sup 2}/R{sub P}+R{sub {mu}{nu}R}{sup {mu}{nu}/}R{sub P} exhibits regular bouncing solutions in both isotropic and anisotropic cases for a wide range of equations of state, including dust (for a<0) and radiation (for arbitrary a). It thus represents a purely gravitational solution to the big bang singularity and anisotropy problems of general relativity without the need for exotic (w>1) sources of matter/energy or extra degrees of freedom.

• OSTI ID: 21432385
• Journal Information: Physical Review. D, Particles Fields, Vol. 82, Issue 8; Other Information: DOI: 10.1103/PhysRevD.82.084015; (c) 2010 American Institute of Physics; ISSN 0556-2821
• Country of Publication: United States
• Language: English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
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EQUATIONS OF STATE
GENERAL RELATIVITY THEORY
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IDEAL FLOW
MATHEMATICAL SOLUTIONS
NONLUMINOUS MATTER
SIMULATION
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