TY - JOUR

T1 - Probing cosmic acceleration beyond the equation of state

T2 - Distinguishing between dark energy and modified gravity models

AU - Ishak, Mustapha

AU - Upadhye, Amol

AU - Spergel, David N.

PY - 2006

Y1 - 2006

N2 - If general relativity is the correct theory of physics on large scales, then there is a differential equation that relates the Hubble expansion function, inferred from measurements of angular diameter distance and luminosity distance, to the growth rate of large scale structure. For a dark energy fluid without couplings or an unusual sound speed, deviations from this consistency relationship could be the signature of modified gravity on cosmological scales. We propose a procedure based on this consistency relation in order to distinguish between some dark energy models and modified gravity models. The procedure uses different combinations of cosmological observations and is able to find inconsistencies when present. As an example, we apply the procedure to a universe described by a recently proposed 5-dimensional modified gravity model. We show that this leads to an inconsistency within the dark energy parameter space detectable by future experiments.

AB - If general relativity is the correct theory of physics on large scales, then there is a differential equation that relates the Hubble expansion function, inferred from measurements of angular diameter distance and luminosity distance, to the growth rate of large scale structure. For a dark energy fluid without couplings or an unusual sound speed, deviations from this consistency relationship could be the signature of modified gravity on cosmological scales. We propose a procedure based on this consistency relation in order to distinguish between some dark energy models and modified gravity models. The procedure uses different combinations of cosmological observations and is able to find inconsistencies when present. As an example, we apply the procedure to a universe described by a recently proposed 5-dimensional modified gravity model. We show that this leads to an inconsistency within the dark energy parameter space detectable by future experiments.

UR - http://www.scopus.com/inward/record.url?scp=33747159334&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33747159334&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.74.043513

DO - 10.1103/PhysRevD.74.043513

M3 - Article

AN - SCOPUS:33747159334

VL - 74

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

SN - 1550-7998

IS - 4

M1 - 043513

ER -