The Impact of Theoretical Uncertainties in the Halo Mass Function and Halo Bias on Precision Cosmology

TL;DR

This paper assesses how theoretical uncertainties in the halo mass function and halo bias affect dark energy constraints from galaxy cluster surveys, emphasizing the need for high-precision predictions to optimize cosmological insights.

Contribution

It quantifies the required accuracy levels for halo mass function and bias predictions to ensure minimal impact on dark energy parameter estimation in upcoming surveys.

Findings

Mass function accuracy needs to be ~1% for DES-like surveys.

Halo bias accuracy requirement is ~5%, less stringent if observable-mass distribution is well constrained.

For large-area, low-mass cluster surveys, mass function and bias must be predicted to ~0.5% and ~1%, respectively.

Abstract

We study the impact of theoretical uncertainty in the dark matter halo mass function and halo bias on dark energy constraints from imminent galaxy cluster surveys. We find that for an optical cluster survey like the Dark Energy Survey, the accuracy required on the predicted halo mass function to make it an insignificant source of error on dark energy parameters is ~ 1%. The analogous requirement on the predicted halo bias is less stringent (~ 5%), particularly if the observable-mass distribution can be well constrained by other means. These requirements depend upon survey area but are relatively insensitive to survey depth. The most stringent requirements are likely to come from a survey over a significant fraction of the sky that aims to observe clusters down to relatively low mass, Mth ~ 10^13.7 Msun/h; for such a survey, the mass function and halo bias must be predicted to accuracies of ~ 0.5% and ~ 1%, respectively. These accuracies represent a limit on the practical need to calibrate ever more accurate halo mass and bias functions. We find that improving predictions for the mass function in the low-redshift and low-mass regimes is the most effective way to improve dark energy constraints.