Using synthetic Lyman-α forests from the Dark Energy Spectroscopic Instrument (DESI) survey, we present a study of the impact of errors in the estimation of quasar redshift on the Lyman-α correlation functions. Estimates of quasar redshift have large uncertainties of a few hundred km s−1 due to the broadness of the emission lines and the intrinsic shifts from other emission lines. We inject Gaussian random redshift errors into the mock quasar catalogues, and measure the auto-correlation and the Lyman-α-quasar cross-correlation functions. We find a smearing of the BAO feature in the radial direction, but changes in the peak position are negligible. However, we see a significant unphysical correlation for small separations transverse to the line of sight which increases with the amplitude of the redshift errors. We interpret this contamination as a result of the broadening of emission lines in the measured mean continuum, caused by quasar redshift errors, combined with the unrealistically strong clustering of the simulated quasars on small scales.
@article{arxiv.2205.06648,
title = {The effect of quasar redshift errors on Lyman-$\alpha$ forest correlation functions},
author = {Samantha Youles and Julian E. Bautista and Andreu Font-Ribera and David Bacon and James Rich and David Brooks and Tamara M. Davis and Kyle Dawson and Govinda Dhungana and Peter Doel and Kevin Fanning and Enrique Gaztañaga and Satya Gontcho A Gontcho and Alma X. Gonzalez-Morales and Julien Guy and Klaus Honscheid and Vid Iršič and Robert Kehoe and David Kirkby and Theodore Kisner and Martin Landriau and Laurent Le Guillou and Michael E. Levi and Axel de la Macorra and Paul Martini and Andrea Muñoz-Gutiérrez and Nathalie Palanque-Delabrouille and Ignasi Pérez-Ràfols and Claire Poppett and César Ramírez-Pérez and Michael Schubnell and Gregory Tarlé and Michael Walther},
journal= {arXiv preprint arXiv:2205.06648},
year = {2022}
}