UCL Discovery

## Direct cosmological inference from three-dimensional correlations of the Lyman-α forest

Gerardi, Francesca; Cuceu, Andrei; Font-Ribera, Andreu; Joachimi, Benjamin; Lemos, Pablo; (2022) Direct cosmological inference from three-dimensional correlations of the Lyman-α forest. Monthly Notices of the Royal Astronomical Society 10.1093/mnras/stac3257. (In press).

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## Abstract

When performing cosmological inference, standard analyses of the Lyman-α (Lyα) three-dimensional correlation functions only consider the information carried by the distinct peak produced by baryon acoustic oscillations (BAO). In this work, we address whether this compression is sufficient to capture all the relevant cosmological information carried by these functions. We do this by performing a direct fit to the full shape, including all physical scales without compression, of synthetic Lyα auto-correlation functions and cross-correlations with quasars at effective redshift zeff = 2.3, assuming a DESI-like survey, and providing a comparison to the classic method applied to the same dataset. Our approach leads to a $3.5{{\ \rm per\ cent}}$ constraint on the matter density ΩM, which is about three to four times better than what BAO alone can probe. The growth term fσ8(zeff) is constrained to the $10{{\ \rm per\ cent}}$ level, and the spectral index ns to $\sim 3-4{{\ \rm per\ cent}}$. We demonstrate that the extra information resulting from our ‘direct fit’ approach, except for the ns constraint, can be traced back to the Alcock-Paczynski effect and redshift space distortion information.

Type: Article Direct cosmological inference from three-dimensional correlations of the Lyman-α forest An open access version is available from UCL Discovery 10.1093/mnras/stac3257 https://doi.org/10.1093/mnras/stac3257 English This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Cosmological parameters, large-scale structure of universe, methods: data analysis UCLUCL > Provost and Vice Provost Offices > UCL BEAMSUCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical SciencesUCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy https://discovery.ucl.ac.uk/id/eprint/10160345