The effect of quasar redshift errors on Lyman-$\alpha$ forest correlation functions

分类： 天文学 >> 天文学 提交时间： 2023-02-19

Samantha Youles Julian E. Bautista Andreu Font-Ribera David Bacon James Rich David Brooks Tamara M. Davis Kyle Dawson Govinda Dhungana Peter Doel Kevin Fanning Enrique Gaztañaga Satya Gontcho A Gontcho Alma X. Gonzalez-Morales Julien Guy Klaus Honscheid Vid Iršič Robert Kehoe David Kirkby Theodore Kisner

摘要： Using synthetic Lyman-$\alpha$ 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-$\alpha$ correlation functions. Estimates of quasar redshift have large uncertainties of a few hundred $\text{km s}^{-1}\,$ 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-$\alpha$-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.

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