Parametrizing modified gravity for cosmological surveys
- Creators
- Gleyzes, Jérôme
Abstract
One of the challenges in testing gravity with cosmology is the vast freedom opened when extending General Relativity. For linear perturbations, one solution consists in using the effective field theory of dark energy. Even then, the theory space is described in terms of a handful of free functions of time. This needs to be reduced to a finite number of parameters to be practical for cosmological surveys. We explore in this article how well simple parametrizations, with a small number of parameters, can fit observables computed from complex theories. Imposing the stability of linear perturbations appreciably reduces the theory space we explore. We find that observables are not extremely sensitive to short time-scale variations and that simple, smooth parametrizations are usually sufficient to describe this theory space. Using the Bayesian information criterion, we find that using two parameters for each function (an amplitude and a power-law index) is preferred over complex models for 86% of our theory space.
Additional Information
© 2017 American Physical Society. Received 12 June 2017; published 15 September 2017. It is a pleasure to thank Alexandre Barreira, Phil Bull, Olivier Doré, Janina Renk, Filippo Vernizzi, and Miguel Zumalacárregui for fruitful discussions and useful comments. Part of the research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This research is partially supported by National Aeronautics and Space Administration (NASA) ROSES ATP 14-ATP14-0093 grant. U.S. Government sponsorship acknowledged.Attached Files
Published - PhysRevD.96.063516.pdf
Submitted - 1705.04714.pdf
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Additional details
- Eprint ID
- 81488
- Resolver ID
- CaltechAUTHORS:20170915-114238718
- NASA/JPL/Caltech
- ATP 14-ATP14-0093
- NASA
- Created
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2017-09-15Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field