Cosmology from clustering of Lyman-alpha galaxies: breaking non-gravitational Lyman-alpha radiative transfer degeneracies using the bispectrum

Understand

Large surveys for Lyman-alpha emitting (LAE) galaxies have been proposed as a new method for measuring clustering of the galaxy population at high redshift with the goal of determining cosmological parameters.

• However, Lyman-alpha radiative transfer effects may modify the observed clustering of LAE galaxies in a way that mimics gravitational effects, potentially reducing the precision of cosmological constraints.
• For example, the effect of the linear redshift-space distortion on the power spectrum of LAE galaxies is potentially degenerate with Lyman-alpha radiative transfer effects owing to the dependence of observed flux on intergalactic medium velocity gradients.
• In this paper, we show that the three-point function (bispectrum) can distinguish between gravitational and non-gravitational effects, and thus breaks these degeneracies, making it possible to recover cosmological parameters from LAE galaxy surveys.