Contiguous redshift parameterizations of the growth index
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75083 (United States)
The growth rate of matter perturbations can be used to distinguish between different gravity theories and to distinguish between dark energy and modified gravity at cosmological scales as an explanation to the observed cosmic acceleration. We suggest here parameterizations of the growth index as functions of the redshift. The first one is given by {gamma}(a)={gamma}-tilde(a)(1/1+(a{sub ttc}/a))+{gamma}{sub early}(1/1+(a/a{sub ttc})), which interpolates between a low/intermediate redshift parameterization {gamma}-tilde(a)={gamma}{sub late}(a)={gamma}{sub 0}+(1-a){gamma}{sub a} and a high redshift {gamma}{sub early} constant value. For example, our interpolated form {gamma}(a) can be used when including the cosmic microwave background to the rest of the data, while the form {gamma}{sub late}(a) can be used otherwise. It is found that the parameterizations proposed achieve a fit that is better than 0.004% for the growth rate in a {lambda}CDM model, better than 0.014% for quintessence-cold-dark-matter models, and better than 0.04% for the flat Dvali-Gabadadze-Porrati model (with {omega}{sub m}{sup 0}=0.27) for the entire redshift range up to z{sub CMB}. We find that the growth index parameters ({gamma}{sub 0},{gamma}{sub a}) take distinctive values for dark energy models and modified gravity models, e.g. (0.5655,-0.027 18) for the {lambda}CDM model and (0.6418, 0.062 61) for the flat Dvali-Gabadadze-Porrati model. This provides a means for future observational data to distinguish between the models.
- OSTI ID:
- 21322425
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 80, Issue 4; Other Information: DOI: 10.1103/PhysRevD.80.043004; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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