TY - JOUR
T1 - Early modified gravity
T2 - Implications for cosmology
AU - Brax, Philippe
AU - Van De Bruck, Carsten
AU - Clesse, Sebastien
AU - Davis, Anne Christine
AU - Sculthorpe, Gregory
PY - 2014/6/13
Y1 - 2014/6/13
N2 - We study the effects of modifications of gravity after big bang nucleosynthesis which would manifest themselves mainly before recombination. We consider their effects on the cosmic microwave background (CMB) radiation and on the formation of large scale structure. The models that we introduce here represent all screened modifications of general relativity which evade the local tests of gravity such as the violation of the strong equivalence principle as constrained by the Lunar Ranging experiment. We use the tomographic description of modified gravity which defines models with screening mechanisms of the chameleon or Damour-Polyakov types and allows one to relate the temporal evolution of the mass and the coupling to matter of a scalar field to its Lagrangian and also to cosmological perturbations. The models with early modifications of gravity all involve a coupling to matter which is stronger in the past leading to effects on perturbations before recombination while minimizing deviations from ΛCDM structure formation at late times. We find that a new family of early transition models lead to discrepancies in the CMB spectrum which could reach a few percent and appear as both enhancements and reductions of power for different scales.
AB - We study the effects of modifications of gravity after big bang nucleosynthesis which would manifest themselves mainly before recombination. We consider their effects on the cosmic microwave background (CMB) radiation and on the formation of large scale structure. The models that we introduce here represent all screened modifications of general relativity which evade the local tests of gravity such as the violation of the strong equivalence principle as constrained by the Lunar Ranging experiment. We use the tomographic description of modified gravity which defines models with screening mechanisms of the chameleon or Damour-Polyakov types and allows one to relate the temporal evolution of the mass and the coupling to matter of a scalar field to its Lagrangian and also to cosmological perturbations. The models with early modifications of gravity all involve a coupling to matter which is stronger in the past leading to effects on perturbations before recombination while minimizing deviations from ΛCDM structure formation at late times. We find that a new family of early transition models lead to discrepancies in the CMB spectrum which could reach a few percent and appear as both enhancements and reductions of power for different scales.
UR - http://www.scopus.com/inward/record.url?scp=84902972872&partnerID=8YFLogxK
U2 - 10.1103/PhysRevD.89.123507
DO - 10.1103/PhysRevD.89.123507
M3 - Article
AN - SCOPUS:84902972872
SN - 1550-7998
VL - 89
JO - Physical Review D - Particles, Fields, Gravitation and Cosmology
JF - Physical Review D - Particles, Fields, Gravitation and Cosmology
IS - 12
M1 - 123507
ER -