Lyman-alpha forest tomography and cross-correlation with cosmic voids

TL;DR

This paper presents the largest 3D map of high-redshift matter fluctuations derived from Lyman-alpha forest data, revealing matter velocity flows around cosmic voids through cross-correlation analysis.

Contribution

It introduces a novel high-redshift matter map from Lyman-alpha data and measures the first velocity flow around voids at z > 2 using cross-correlation.

Findings

First high-redshift void catalog from Lyman-alpha tomography

Detection of matter velocity flow around voids at z > 2

Good agreement with linear velocity models

Abstract

The Lyman-alpha forest is a unique probe of large-scale matter density fluctuations at high redshift (z > 2). It is possible to obtain 3D maps of the matter distribution from Lyman-alpha data, using tomographic reconstruction methods. Here, we present the largest tomographic map of matter fluctuations at z > 2, over the Gpc^3 volume covered by Lyman-alpha forest from SDSS-IV quasar spectra in the Stripe 82 field. We present a catalog of high-redshift voids constructed from this map. The measurement of the cross-correlation between these voids and the Lyman-alpha forest provides the first observation of the matter velocity flow around voids, through the RSD effect, at such high redshift. The data is in good agreement with simulations and is well adjusted with a linear, Kaiser velocity model.