Journal
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
Volume -, Issue 4, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/1475-7516/2018/04/063
Keywords
dark energy theory; modified gravity; power spectrum; cosmological parameters from LSS
Funding
- University of Portsmouth
- U.K. Science and Technologies Facilities Council [ST/N000668/1]
- European Research Council (ERC) under the European Union's Horizon research and innovation programme [646702]
- Enhanced Eurotalents fellowship, a Marie Sklodowska-Curie Actions Programme
- Programme National de Cosmologie and Galaxies (PNCG) of CNRS/INSU, France
- French Agence Nationale de la Recherche [ANR-12-BS05-0002]
- STFC [ST/N000668/1, ST/J005428/1] Funding Source: UKRI
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We compare analytical computations with numerical simulations for dark-matter clustering, in general relativity and in the normal branch of DGP gravity (nDGP). Our analytical frameword is the Effective Field Theory of Large-Scale Structure (EFTofLSS), which we use to compute the one-loop dark-matter power spectrum, including the resummation of infrared bulk displacement effects. We compare this to a set of 20 COLA simulations at redshifts z = 0, z = 0.5, and z = 1, and fit the free parameter of the EFTofLSS, called the speed of sound, in both ACDM and nDGP at each redshift. At one-loop at z = 0, the reach of the EFTofLSS is k(reach) approximate to 0.14 hMpc(-1) for both ACDM and nDGP. Along the way, we compare two different infrared resummation schemes and two different treatments of the time dependence of the perturbative expansion, concluding that they agree to approximately 1% over the scales of interest. Finally, we use the ratio of the COLA power spectra to make a precision measurement of the difference between the speeds of sound in ACDM and nDGP, and verify that this is proportional to the modification of the linear coupling constant of the Poisson equation.
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