A Spectroscopic Road Map for Cosmic Frontier: DESI, DESI-II, Stage-5

TL;DR

This white paper outlines a strategic plan for future spectroscopic cosmology experiments beyond DESI, emphasizing higher density and redshift coverage to address fundamental questions about inflation, dark energy, and dark matter.

Contribution

It proposes a detailed roadmap for next-generation spectroscopic surveys, including DESI-II and Stage-5, to enhance cosmological measurements and complement other observational methods.

Findings

DESI will map 40 million galaxies and quasars up to z=1.2.

Future experiments will target higher redshifts and densities.

These surveys will significantly improve constraints on cosmological parameters.

Abstract

In this white paper, we present an experimental road map for spectroscopic experiments beyond DESI. DESI will be a transformative cosmological survey in the 2020s, mapping 40 million galaxies and quasars and capturing a significant fraction of the available linear modes up to z=1.2. DESI-II will pilot observations of galaxies both at much higher densities and extending to higher redshifts. A Stage-5 experiment would build out those high-density and high-redshift observations, mapping hundreds of millions of stars and galaxies in three dimensions, to address the problems of inflation, dark energy, light relativistic species, and dark matter. These spectroscopic data will also complement the next generation of weak lensing, line intensity mapping and CMB experiments and allow them to reach their full potential.