Correlations of fluctuations of the flux in Lyman-α forests of high-redshift quasars have been observed by the Baryonic Acoustic Oscillation Spectroscopy Survey (BOSS) and the Dark Energy Spectroscopy Instrument (DESI) survey where they have revealed the effects of baryon acoustic oscillations (BAO). In order to fit the correlation functions to a physical model and thereby constrain cosmological parameters, it is necessary to take into account the effects of fitting the observed spectra to a template about which the fluctuations are measured. In this paper we use mock spectra to test the distortion matrix technique that has been used since the final BOSS data release to appropriately distort the models. We show that while percent-level effects on the derived forest bias parameters may be present, the technique works sufficiently well that the determination of the BAO peak position is not affected at the percent level. We introduce modifications in the technique used by DESI that were not in the original applications and suggest further possibilities for improvements.
@article{arxiv.2506.15262,
title = {The effects of continuum fitting on Lyman-$\alpha$ forest correlations},
author = {Nicolas Busca and James Rich and Julian Bautista and Andrei Cuceu and Andreu Font-Ribera and Julien Guy and Hiram K. Herrera-Alcantar and Julianna Stermer and Christophe Balland and J. Aguilar and S. Ahlen and D. Bianchi and D. Brooks and T. Claybaugh and A. de la Macorra and P. Doel and S. Ferraro and J. E. Forero-Romero and E. Gaztañaga and C. Gordon and G. Gutierrez and M. Ishak and R. Kehoe and D. Kirkby and A. Kremin and M. Landriau and L. Le Guillou and C. Magneville and P. Martini and R. Miquel and S. Nadathur and N. Palanque-Delabrouille and F. Prada and I. Pérez-Ràfols and C. Ravoux and G. Rossi and E. Sanchez and D. Schlegel and H. Seo and J. Silber and D. Sprayberry and G. Tarlé and B. A. Weaver and R. Zhou and H. Zou},
journal= {arXiv preprint arXiv:2506.15262},
year = {2025}
}