COMAP Early Science. V. Constraints and Forecasts at z ∼ 3

Abstract We present the current state of models for z ∼ 3 carbon monoxide (CO) line intensity signal targeted by CO Mapping Array Project (COMAP) Pathfinder in context its early science results. Our fiducial model, relating dark matter halo properties to luminosities, informs parameter priors with empirical galaxy–halo connection and previous (1–0) observations. The data spanning wavenumbers k = 0.051–0.62 Mpc −1 represent first direct 3D constraint on clustering component power spectrum. 95% upper limit redshift-space amplitude A clust ≲ 70 μ K 2 greatly improves indirect 420 reported from Power Spectrum Survey (COPSS) measurement at 1 . COMAP excludes a subset literature constrains interpretation COPSS results, demonstrating complementary nature interferometric surveys. Using bias expectations our priors, we also constrain squared mean intensity–bias product, Tb 2 50 , cosmic molecular gas density, ρ H2 < 2.5 × 10 8 M ⊙ −3 (95% limits). Based instrument performance estimates, forecast that 5 yr campaign will detect spectrum overall signal-to-noise ratio 9–17. Between then now, expect CO–galaxy cross-spectrum using overlapping galaxy survey data, enabling enhanced inferences star formation evolution history.