Connecting CO Intensity Mapping to Molecular Gas and Star Formation in the Epoch of Galaxy Assembly

TL;DR

This paper predicts the CO(1-0) intensity map and power spectrum at redshifts 2.4-2.8, demonstrating its potential to infer properties of high-redshift galaxies and their molecular gas content through intensity mapping.

Contribution

It introduces a parameterized model linking galaxy properties to the intensity mapping signal and demonstrates how to constrain galaxy and molecular gas properties using simulated observations.

Findings

The fiducial model predicts detectable CO intensity maps at z~2.4-2.8.

Varying model parameters significantly affects the power spectrum.

MCMC analysis constrains the LIR-LCO relation and CO luminosity function.

Abstract

Intensity mapping, which images a single spectral line from unresolved galaxies across cosmological volumes, is a promising technique for probing the early universe. Here we present predictions for the intensity map and power spectrum of the CO(1-0) line from galaxies at z ~ 2.4 -2.8, based on a parameterized model for the galaxy-halo connection, and demonstrate the extent to which properties of high-redshift galaxies can be directly inferred from such observations. We find that our fiducial prediction should be detectable by a realistic experiment. Motivated by significant modeling uncertainties, we demonstrate the effect on the power spectrum of varying each parameter in our model. Using simulated observations, we infer constraints on our model parameter space with an MCMC procedure, and show corresponding constraints on the LIR-LCO relation and the CO luminosity function. These constraints would be complementary to current high-redshift galaxy observations, which can detect the brightest galaxies but not complete samples from the faint end of the luminosity function. By probing these populations in aggregate, CO intensity mapping could be a valuable tool for probing molecular gas and its relation to star formation in high-redshift galaxies.