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

Understand

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.