A coarse grained perturbation theory for the Large Scale Structure, with cosmology and time independence in the UV

Abstract

Standard cosmological perturbation theory (SPT) for the Large Scale Structure (LSS) of the Universe fails at small scales (UV) due to strong nonlinearities and to multistreaming effects. In Pietroni et al. 2011 a new framework was proposed in which the large scales (IR) are treated perturbatively while the information on the UV, mainly small scale velocity dispersion, is obtained by nonlinear methods like N-body simulations. Here we develop this approach, showing that it is possible to reproduce the fully nonlinear power spectrum (PS) by combining a simple (and fast) 1-loop computation for the IR scales and the measurement of a single, dominant, correlator from N-body simulations for the UV ones. We measure this correlator for a suite of seven different cosmologies, and we show that its inclusion in our perturbation scheme reproduces the fully non-linear PS with percent level accuracy, for wave numbers up to $k\sim 0.4h\mathrm{Mp}{\mathrm{c}}^{-1}$ down to $z=0$. We then show that, once this correlator has been measured in a given cosmology, there is no need to run a new simulation for a different cosmology in the suite. Indeed, by rescaling this correlator by a proper function computable in SPT, the reconstruction procedure works also for the other cosmologies and for all redshifts, with comparable accuracy. Finally, we clarify the relation of this approach to the Effective Field Theory methods recently proposed in the LSS context.

arXiv comment37 pages, 9 figures; published on JCAP

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Cited by in corpus (26)

• A Lagrangian effective field theory
• The Effective Field Theory of Large Scale Structure at Two Loops: the apparent scale dependence of the speed of sound
• The Gaussian streaming model and Lagrangian effective field theory
• Galaxy Bispectrum from Massive Spinning Particles
• Cosmological perturbation theory in 1+1 dimensions
• Structure formation with massive neutrinos: going beyond linear theory
• Systematic Renormalization of the Effective Theory of Large Scale Structure
• Large scale structure from viscous dark matter
• Constraints on modified gravity from the BOSS galaxy survey
• FFT-PT: Reducing the two-loop large-scale structure power spectrum to low-dimensional radial integrals
• Structure formation beyond shell-crossing: nonperturbative expansions and late-time attractors
• Cosmological perturbations for two cold fluids in $\Lambda$CDM
• Renormalization-group flow of the effective action of cosmological large-scale structures
• Fitting and forecasting non-linear coupled dark energy
• Galilean invariant resummation schemes of cosmological perturbations
• Evolution of dark matter velocity dispersion
• Fisher matrix for the one-loop galaxy power spectrum: measuring expansion and growth rates without assuming a cosmological model
• Modeling iterative reconstruction and displacement field in the large scale structure
• Asymptotic expansions for the Large Scale Structure
• Improving precision and accuracy in cosmology with model-independent spectrum and bispectrum
• Coarse-grained cosmological perturbation theory: stirring up the dust model
• Renormalizing a Viscous Fluid Model for Large Scale Structure Formation
• The dark matter bispectrum from effective viscosity and one-particle irreducible vertices
• Efficient implementation of the Time Renormalization Group
• Nonlinear evolution of density and flow perturbations on a Bjorken background
• The Large Scale Structure Bootstrap: perturbation theory and bias expansion from symmetries