Non-linear matter power spectrum without screening dynamics modelling in $f(R)$ gravity

Abstract

Halo model is a physically intuitive method for modelling the non-linear power spectrum, especially for the alternatives to the standard $\Lambda$CDM models. In this paper, we exam the Sheth-Tormen barrier formula adopted in the previous \texttt{CHAM} method \citep{2018MNRAS.476L..65H}. As an example, we model the ellipsoidal collapse of top-hat dark matter haloes in $f(R)$ gravity. A good agreement between Sheth-Tormen formula and our result is achieved. The relative difference in the ellipsoidal collapse barrier is less than or equal to $1.6\%$. Furthermore, we verify that, for F4 and F5 cases of Hu-Sawicki $f(R)$ gravity, the screening mechanism do not play a crucial role in the non-linear power spectrum modelling up to $k\sim 1[h/\mathrm{Mpc}]$. We compare two versions of modified gravity modelling, namely with/without screening. We find that by treating the effective Newton constant as constant number ($G_{\mathrm{eff}}=4/3G_N$) is acceptable. The scale dependence of the gravitational coupling is sub-relevant. The resulting spectra in F4 and F5, are in $0.1\%$ agreement with the previous \texttt{CHAM} results. The published code is accelerated significantly. Finally, we compare our halo model prediction with N-body simulation. We find that the general spectrum profile agree, qualitatively. However, via the halo model approach, there exists a systematic under-estimation of the matter power spectrum in the co-moving wavenumber range between $0.3h/\mathrm{Mpc}$ and $3h/\mathrm{Mpc}$. These scales are overlapping with the transition scales from two halo term dominated regimes to those of one halo term dominated.

Accepted in MNRAS

References in corpus (15)

• Models of f(R) Cosmic Acceleration that Evade Solar-System Tests
• Searching for modified growth patterns with tomographic surveys
• Non-linear Evolution of f(R) Cosmologies III: Halo Statistics
• Testing gravity with CAMB and CosmoMC
• Non-linear evolution of f(R) cosmologies II: power spectrum
• Initial Conditions for Large Cosmological Simulations
• Effective Field Theory of Cosmic Acceleration: constraining dark energy with CMB data
• Constraining chameleon models with cosmology
• MGCAMB with massive neutrinos and dynamical dark energy
• A comparison of Einstein-Boltzmann solvers for testing General Relativity
• The contributions of matter inside and outside of haloes to the matter power spectrum
• Perturbation theory and excursion set estimates of the probability distribution function of dark matter, and a method for reconstructing the initial distribution function
• A parametrisation of modified gravity on nonlinear cosmological scales
• Ellipticity Weakens Chameleon Screening
• Convolution Lagrangian perturbation theory for biased tracers beyond general relativity

Cited by in corpus (2)

• On the road to percent accuracy IV: ReACT -- computing the non-linear power spectrum beyond $\Lambda$CDM
• Universality of the halo mass function in modified gravity cosmologies