TARDIS Paper II: Synergistic Density Reconstruction from Lyman-alpha Forest and Spectroscopic Galaxy Surveys with Applications to Protoclusters and the Cosmic Web

TL;DR

This paper enhances the TARDIS method to jointly reconstruct matter density fields at Cosmic Noon using Lyman-alpha forest and galaxy survey data, improving accuracy and enabling evolution to z=0 for protocluster analysis.

Contribution

It introduces a joint reconstruction approach combining multiple tracers, leading to more precise density and velocity fields and enabling evolution studies of protoclusters.

Findings

Joint analysis improves power spectrum reconstruction at high scales.

Reconstruction is equivalent to a denser Lyman-alpha survey.

Accurate mass estimates of protoclusters and their evolution to z=0.

Abstract

In this work we expand upon the Tomographic Absorption Reconstruction and Density Inference Scheme (TARDIS) in order to include multiple tracers while reconstructing matter density fields at Cosmic Noon (z ~ 2-3). In particular, we jointly reconstruct the underlying density field from simulated Lyman-Alpha forest observations at $z\sim 2.5$ and an overlapping galaxy survey. We find that these data are synergistic, with the Lyman Alpha forest providing reconstruction of low density regions and galaxy surveys tracing the density peaks. We find a more accurate power spectra reconstruction going to higher scales when fitting these two data-sets simultaneously than if using either one individually. When applied to cosmic web analysis, we find performing the joint analysis is equivalent to a Lyman Alpha survey with significantly increased sight-line spacing. Since we reconstruct the velocity field and matter field jointly, we demonstrate the ability to evolve the mock observed volume further to z=0, allowing us to create a rigorous definition of "proto-cluster" as regions which will evolve into clusters. We apply our reconstructions to study protocluster structure and evolution, finding for realistic survey parameters we can provide accurate mass estimates of the z \approx 2 structures and their z = 0 fate.