Non-linearities in the Lyman-$\alpha$ forest and in its cross-correlation with dark matter halos

Abstract

Three-dimensional correlations of the Lyman-$\alpha$ (Ly$\alpha$) forest and cross correlations between the Ly$\alpha$ forest and quasars have been measured on large scales, allowing a precise measurement of the baryon acoustic oscillation (BAO) feature at redshifts $z>2$. These 3D correlations are often modelled using linear perturbation theory, but full-shape analyses to extract cosmological information beyond BAO will require more realistic models capable of describing non-linearities present at smaller scales. We present a measurement of the Ly$\alpha$ forest flux power spectrum from large hydrodynamic simulations -- the Sherwood simulations -- and compare it to different models describing the small-scale deviations from linear theory. We confirm that the model presented in Arinyo-i-Prats et al. (2015) fits the measured 3D power up to $k=10h\mathrm{Mp}{\mathrm{c}}^{-1}$ with an accuracy better than 5%, and show that the same model can also describe the 1D correlations with similar precision. We also present, for the first time, an equivalent study for the cross-power spectrum of halos with the Ly$\alpha$ forest, and we discuss different challenges we face when modelling the cross-power spectrum beyond linear scales. We make all our measured power spectra public in \url{https://github.com/andreufont/sherwood_p3d}. This study is a step towards joint analyses of 1D and 3D flux correlations, and towards using the quasar-Ly$\alpha$ cross-correlation beyond BAO analyses.

31 pages, 19 figures

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Cited by in corpus (11)

• DESI 2024 IV: Baryon Acoustic Oscillations from the Lyman Alpha Forest
• Constraints on the cosmic expansion rate at redshift 2.3 from the Lyman-$\alpha$ forest
• The 3D Lyman-$\alpha$ Forest Power Spectrum from eBOSS DR16
• The ACCEL2 Project: Precision Measurements of EFT Parameters and BAO Peak Shifts for the Lyman-$\alpha$ Forest
• Planting a Lyman alpha forest on AbacusSummit
• Measurement of the small-scale 3D Lyman-$\alpha$ forest power spectrum
• Fresh Look at Neutrino Self-Interactions With the Lyman-$\alpha$ Forest: Constraints from EFT and PRIYA Simulations
• The Compressed 3D Lyman-Alpha Forest Bispectrum
• ForestFlow: predicting the Lyman-$\alpha$ forest clustering from linear to nonlinear scales
• 3D Correlations in the Lyman-$\alpha$ Forest from Early DESI Data
• Modeling the Cosmological Lyman-$\alpha$ Forest at the Field Level