Browsing by Autor "Andreu Font-Ribera"

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    Modelling the impact of quasar redshift errors on the full-shape analysis of correlations in the Lyman-α forest
    (Oxford University Press, 2025) C. Gordon; Andrei Cuceu; Andreu Font-Ribera; H. K. Herrera-Alcantar; Jessica Nicole Aguilar Steven Ahlen; D. Bianchi; David H. Brooks; T. Claybaugh; Shaun Cole; Axel de la Macorra
    ABSTRACT In preparation for the first cosmological measurements from the full shape of the Lyman-$\alpha$ (Ly $\alpha$) forest from Dark Energy Spectroscopic Instrument (DESI), we must carefully model all relevant systematics that might bias our analysis. It has been shown that random quasar redshift errors produce a smoothing effect on the mean quasar continuum in the Ly $\alpha$ forest region. This, in turn, gives rise to spurious features in the Ly $\alpha$ autocorrelation and its cross-correlation with quasars. Using synthetic data sets based on the DESI survey, we confirm that the impact on baryon acoustic oscillation measurements is small, but that a bias is introduced to parameters which depend on the full shape of our correlations. We combine a model of this contamination in the cross-correlation with a new model we introduce here for the autocorrelation. These are parametrized by three parameters, which, when included in a joint fit to both correlation functions, successfully eliminate any impact of redshift errors on our full-shape constraints. We also present a strategy for removing this contamination from real data, by removing $\sim$0.3 per cent of correlating pairs.