Measuring and unbiasing the BAO shift in the Lyman-Alpha forest with AbacusSummit

Understand

The currently observing Dark Energy Spectroscopic Instrument (DESI) places sub-percent constraints on the Baryon Acoustic Oscillations (BAO) scaling parameters from the Lyman-$\alpha$ (Ly-$\alpha$) forest.

• However, no systematic error budget stemming from non-linearities in the 3D clustering of the Ly-$\alpha$ forest is included in the DESI-Ly-$\alpha$ analysis.
• In this work, we measure the size of the shift of the BAO peak using large Ly-$\alpha$ forest mocks produced on the $N$-body simulation suite \textsc{AbacusSummit}.
• Specifically, we measure the Ly-$\alpha$ auto-correlation and the Ly-$\alpha$-quasar cross-correlation functions.