Description
The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) will transform extragalactic astronomy by providing an unprecedented volume of imaging data. With limited resources for spectroscopic follow-up, photometric redshifts will be essential for studying distant galaxies. However, the choice of intergalactic medium (IGM) absorption model can significantly impact photometric redshift estimates at high redshifts (z > 3), with some models systematically shifting redshifts to lower values by up to 5%. Here, we present an updated IGM absorption model informed by recent observational measurements of Lyman-alpha transmission and Lyman-limit systems, particularly at high redshifts. We assess the performance of this model against three widely used IGM prescriptions (Madau 1995, Meiksin 2006, and Inoue et al. 2014) by deriving photometric redshifts for a sample of ~30,000 quasars with spectroscopic redshifts in the range $2
