An Improved Fit for Linear Halo Bias at High Redshift

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.