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Beyond the growth rate of cosmic structure: testing modified gravity models with an extra degree of freedom
journal contribution
posted on 2023-06-09, 06:27 authored by Clare Burrage, David Parkinson, David SeeryDavid SeeryIn 'modified' gravity the observed acceleration of the universe is explained by changing the gravitational force law or the number of degrees of freedom in the gravitational sector. Both possibilities can be tested by measurements of cosmological structure formation. In this paper we elaborate the details of such tests using the Galileon model as a case study. We pay attention to the possibility that each new degree of freedom may have stochastically independent initial conditions, generating different types of potential well in the early universe and breaking complete correlation between density and velocity power spectra. This 'stochastic bias' can confuse schemes to parametrize the predictions of modified gravity models, such as the use of the growth parameter f alone. Using data from the WiggleZ Dark Energy Survey we show that it will be possible to obtain constraints using information about the cosmological-scale force law embedded in the multipole power spectra of redshift-space distortions. As an example, we obtain an upper limit on the strength of the conformal coupling to matter in the cubic Galileon model, giving |1/M| < 200/M_P. This allows the fifth-force to be stronger than gravity, but is consistent with zero coupling.
Funding
Astronomy rolling grant; G0278; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/I000976/1
Astrophysics and Cosmology - Sussex Consolidated Grant; G1291; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/L000652/1
History
Publication status
- Published
File Version
- Accepted version
Journal
Physical Review DISSN
2470-0010Publisher
American Physical SocietyExternal DOI
Issue
4Volume
96Department affiliated with
- Physics and Astronomy Publications
Research groups affiliated with
- Astronomy Centre Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2017-05-31First Open Access (FOA) Date
2017-08-29First Compliant Deposit (FCD) Date
2017-05-31Usage metrics
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