The clustering of Ly-alpha emitters in a LambdaCDM Universe

TL;DR

This study combines a semi-analytical galaxy formation model with a large LambdaCDM simulation to predict Ly-alpha emitter clustering, revealing its dependence on redshift and providing insights for future survey designs.

Contribution

It presents the first large-volume simulation-based predictions of Ly-alpha emitter clustering, accounting for sample variance and guiding future observational strategies.

Findings

Clustering strength weakly depends on Ly-alpha luminosity.

Clustering strongly depends on redshift, increasing at higher redshifts.

Mock catalogues match current survey measurements but show significant scatter.

Abstract

We combine a semi-analytical model of galaxy formation with a very large simulation which follows the growth of large scale structure in a LambdaCDM universe to predict the clustering of Ly-alpha emitters. We find that the clustering strength of Ly-alpha emitters has only a weak dependence on Ly-alpha luminosity but a strong dependence on redshift. With increasing redshift, Ly-alpha emitters trace progressively rarer, higher density regions of the universe. Due to the large volume of the simulation, over 100 times bigger than any previously used for this application, we can construct mock catalogues of Ly-alpha emitters and study the sample variance of current and forthcoming surveys. We find that the number and clustering of Ly-alpha emitters in our mock catalogues are in agreement with measurements from current surveys, but that there is a considerable scatter in these quantities. We argue that a proposed survey of emitters at z=8.8 should be extended significantly in solid angle to allow a robust measurement of Ly-alpha emitter clustering.