Measurements of the z > 5 Lyman-α forest flux auto-correlation functions from the extended XQR-30 data set
Abstract
Recently, the Lyman-α (Lyα) forest flux auto-correlation function has been shown to be sensitive to the mean free path of hydrogen-ionizing photons, λmfp, for simulations at z ≥ 5.4. Measuring λmfp at these redshifts will give vital information on the ending of reionization. Here we present the first observational measurements of the Lyα forest flux auto-correlation functions in ten redshift bins from 5.1 ≤ z ≤ 6.0. We use a sample of 35 quasar sightlines at z > 5.7 from the extended XQR-30 data set, this data has signal-to-noise ratios of > 20 per spectral pixel. We carefully account for systematic errors in continuum reconstruction, instrumentation, and contamination by damped Lyα systems. With these measurements, we introduce software tools to generate auto-correlation function measurements from any simulation. For an initial comparison, we show our auto-correlation measurements with simulation models for recently measured λmfp values and find good agreements. Further work in modeling and understanding the covariance matrices of the data is necessary to get robust measurements of λmfp from this data.