Snowmass2021 Cosmic Frontier White Paper: High Density Galaxy Clustering in the Regime of Cosmic Acceleration

TL;DR

This white paper discusses the potential of high-density galaxy clustering studies at redshifts below 1.5, emphasizing how future spectroscopic surveys can significantly improve tests of dark energy, neutrino masses, and beyond-standard-model physics.

Contribution

It proposes a coordinated program combining simulations, theory, and future spectroscopy to enhance cosmological tests during cosmic acceleration.

Findings

High-density galaxy surveys can surpass current constraints.

Future spectroscopic observations will improve dark energy measurements.

Enhanced tests of neutrino masses and new physics are possible.

Abstract

Joint studies of imaging and spectroscopic samples, informed by theory and simulations, offer the potential for comprehensive tests of the cosmological model over redshifts z<1.5. Spectroscopic galaxy samples at these redshifts can be increased beyond the planned Dark Energy Spectroscopic Instrument (DESI) program by at least an order of magnitude, thus offering significantly more constraining power for these joint studies. Spectroscopic observations of these galaxies in the latter half of the 2020's and beyond would leverage the theory and simulation effort in this regime. In turn, these high density observations will allow enhanced tests of dark energy, physics beyond the standard model, and neutrino masses that will greatly exceed what is currently possible. Here, we present a coordinated program of simulations, theoretical modeling, and future spectroscopy that would enable precise cosmological studies in the accelerating epoch where the effects of dark energy are most apparent.