The BAHAMAS project: Evaluating the accuracy of the halo model in predicting the non-linear matter power spectrum

Abstract

The halo model formalism is widely adopted in cosmological studies for predicting the growth of large-scale structure in the Universe. However, to date there have been relatively few direct comparisons of the halo model with more accurate (but much more computationally expensive) cosmological simulations. We test the accuracy of the halo model in reproducing the non-linear matter power spectrum, P(k), when the main inputs of the halo model (specifically the matter density profiles, halo mass function, and linear bias) are taken directly from the BAHAMAS simulations and we assess how well the halo model reproduces P(k) from the same simulations. We show that the halo model generally reproduces P(k) in the deep non-linear regime (1-halo) to typically a few percent accuracy, but struggles to reproduce (approx. 15% error) P(k) at intermediate scales of 0.1 < k [h/ Mpc] < 3 at z=0, marking the transition between the 1-halo and 2-halo terms. We show that the magnitude of this error is a strong function of the halo mass definition (through its effects on radial extent of haloes) and of redshift. Furthermore, we test the accuracy of the halo model in recovering the relative impact of baryons on P(k). We show that the systematic errors in recovering the absolute P(k) largely cancel when considering the relative impact of baryons. This suggests that the halo model can make precise predictions for the baryonic suppression, offering a fast and accurate way to adjust collisionless matter power spectra for the presence of baryons and associated processes.

16 pages, 11 figures, accepted for publication in MNRAS

References in corpus (16)

• Baryon effects on the internal structure of LCDM halos in the EAGLE simulations
• A universal model for halo concentrations
• Non-linear Least Squares Fitting in IDL with MPFIT
• The Scale Dependence of Halo and Galaxy Bias: Effects in Real Space
• Modelling baryonic feedback for survey cosmology
• The Mira-Titan Universe II: Matter Power Spectrum Emulation
• The effect of baryons on the inner density profiles of rich clusters
• A hydrodynamical halo model for weak-lensing cross correlations
• The halo model in a massive neutrino cosmology
• The contributions of matter inside and outside of haloes to the matter power spectrum
• Nonlinear clustering in models with primordial non-Gaussianity: the halo model approach
• Including beyond-linear halo bias in halo models
• A high precision semi-analytic mass function
• Connecting the structure of dark matter haloes to the primordial power spectrum
• The Effective Halo Model: Creating a Physical and Accurate Model of the Matter Power Spectrum and Cluster Counts
• Probing Cosmology and Cluster Astrophysics with Multi-Wavelength Surveys I. Correlation Statistics

Cited by in corpus (1)

• SP(k) -- A hydrodynamical simulation-based model for the impact of baryon physics on the non-linear matter power spectrum