Modeling the small-scale Lyman-alpha forest

Abstract: Three-dimensional correlations of the Lyman-alpha forest and cross correlations between the Lyman-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. In this talk, I present recent work looking at the Lyman-alpha flux power spectrum and the Lyman-alpha-halo cross-power spectrum measured in the Sherwood simulations. I compare these measurements to different models describing the small-scale deviations from linear theory. Our work confirms that the model presented in Arinyo-i-Prats et al. (2015) fits the measured Lyman-alpha 3D power up to k=10 h/Mpc with an accuracy better than 5% and shows that the same model can also describe the 1D correlations with similar precision. A new model we develop appears capable of describing the Lyman-alpha-halo cross-power spectrum within a few percent up to k=1 h/Mpc.