Characterization of contaminants in the Lyman-alpha forest auto-correlation with DESI

Understand

Baryon Acoustic Oscillations can be measured with sub-percent precision above redshift two with the Lyman-alpha forest auto-correlation and its cross-correlation with quasar positions.

• This is one of the key goals of the Dark Energy Spectroscopic Instrument (DESI) which started its main survey in May 2021.
• We present in this paper a study of the contaminants to the lyman-alpha forest which are mainly caused by correlated signals introduced by the spectroscopic data processing pipeline as well as astrophysical contaminants due to foreground absorption in the intergalactic medium.
• Notably, an excess signal caused by the sky background subtraction noise is present in the lyman-alpha auto-correlation in the first line-of-sight separation bin.