The Lyman-a forest is a unique large-scale structure tracer at Mpc scales and below at high redshifts (2 < z < 4). One of the key advantages of the Lyman-a forest is that, since the density fields are only mildly non-linear at the respective redshifts, a much wider range of scales can be used to robustly probe cosmology than with most galaxy surveys, making the Lyman-a fluctuations a powerful probe of early-Universe physics when combined with tracers that are sensitive to very large scales, e.g,~cosmic microwave background anisotropies. I will discuss the 3D Lyman-a forest power spectrum and how to perform full-shape cosmological analyses of Lyman-a forest data in the framework of the effective field theory of large-scale structure as well as cross-correlations of CMB lensing with the Lyman-a forest at the field level. These methods pave the way for cosmological analyses of eBOSS, DESI and future spectroscopic surveys.
Jonás Chaves Montero, Andreu Font Ribera, Martine Lokken