Presentation #209.01 in the session Cosmology I.
The CO Mapping Array Project (COMAP) is undertaking a three-dimensional measurement of fluctuations in the integrated intensity of CO line emission at redshifts spanning the epochs of galaxy assembly and reionisation (‘cosmic noon’ and ‘cosmic dawn’), applying the technique of intensity mapping to survey both faint and bright CO emission across large comoving volumes. The COMAP Pathfinder experiment targets the CO(1-0) line intensity power spectrum at redshifts 2.4-3.4, using a dedicated receiver and telescope at the Owens Valley Radio Observatory. Observations began in late summer 2019 and are expected to continue until at least 2024. Using an early science result representing 450 hours of integration time across 12 square degrees of sky, we are able to place an upper limit on the clustering component of the CO power spectrum for the first time. With this limit, we exclude various models in the literature and derive limits on cosmic molecular gas abundance consistent with previous constraints from both other CO intensity mapping experiments and searches for individual CO line candidates. These early results already strongly demonstrate the complementarity of single-dish CO intensity mapping to interferometric CO surveys. Based on early instrument performance and our fiducial model of the CO signal, we forecast a detection of the CO power spectrum by the end of the initial five years of observations. Even before achieving that detection, we expect a detection of the CO-galaxy cross power spectrum using overlapping galaxy survey data with COMAP data, which will enable enhanced inferences of cosmic star-formation and galaxy evolution history.