An Improved Fit for Linear Halo Bias at High Redshift

TL;DR

This paper refines the linear halo bias model at high redshifts (z=6-19), reducing systematic errors to below 1%, which aids in interpreting early-Universe galaxy clustering data from upcoming surveys.

Contribution

It provides an improved linear bias fit for dark matter halos at high redshifts, addressing inaccuracies in previous models and supporting future cosmological analyses.

Findings

Halo biases at z=6-19 are 3-4% higher than low-redshift calibrations.

The new fit reduces systematic offset to less than 1%.

Results facilitate better interpretation of early-Universe galaxy clustering.

Abstract

High- to ultrahigh-redshift clustering of halos provides a powerful tool to understand cosmology and galaxy formation. However, theoretical predictions are not firmly established in the first billion years, where current and upcoming surveys are beginning to reach percent-level precision. Here we measure dark matter halo biases at $z=6$ - 19 from simulation data, and find they are $\sim$ 3 - 4$\%$ higher than canonical results calibrated at low $z$. We provide an updated linear-bias fit at these early times, reducing the mean systematic offset to $< 1\%$. These results will enable robust interpretation of early-Universe galaxy clustering from JWST, Roman, and intensity-mapping surveys.