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We present the current state of models for the z ∼ 3 carbon monoxide (CO) line intensity signal targeted by the CO Mapping Array Project (COMAP) Pathfinder in the context of its early science results. Our fiducial model, relating dark matter halo properties to CO luminosities, informs parameter priors with empirical models of the galaxyâ€"halo connection and previous CO (1â€"0) observations. The Pathfinder early science data spanning wavenumbers k = 0.051â€"0.62 Mpcâˆ'1 represent the first direct 3D constraint on the clustering component of the CO (1â€"0) power spectrum. Our 95% upper limit on the redshift-space clustering amplitude A clust ≲ 70 ÎĽ K2 greatly improves on the indirect upper limit of 420 ÎĽ K2 reported from the CO Power Spectrum Survey (COPSS) measurement at k ∼ 1 Mpcâˆ'1. The COMAP limit excludes a subset of models from previous literature and constrains interpretation of the COPSS results, demonstrating the complementary nature of COMAP and interferometric CO surveys. Using line bias expectations from our priors, we also constrain the squared mean line intensityâ€"bias product, Tb 2 ≲ 50 ÎĽ K2, and the cosmic molecular gas density, ρ H2 < 2.5 Ă— 108 M ⊙ Mpcâˆ'3 (95% upper limits). Based on early instrument performance and our current CO signal estimates, we forecast that the 5 yr Pathfinder campaign will detect the CO power spectrum with overall signal-to-noise ratio of 9â€"17. Between then and now, we also expect to detect the COâ€"galaxy cross-spectrum using overlapping galaxy survey data, enabling enhanced inferences of cosmic star formation and galaxy evolution history. [ABSTRACT FROM AUTHOR]

We introduce COMAP- EoR, the next generation of the Carbon Monoxide Mapping Array Project aimed at extending CO intensity mapping to the Epoch of Reionization. COMAP- EoR supplements the existing 30 GHz COMAP Pathfinder with two additional 30 GHz instruments and a new 16 GHz receiver. This combination of frequencies will be able to simultaneously map CO(1â€"0) and CO(2â€"1) at reionization redshifts (z ∼ 5â€"8) in addition to providing a significant boost to the z ∼ 3 sensitivity of the Pathfinder. We examine a set of existing models of the EoR CO signal, and find power spectra spanning several orders of magnitude, highlighting our extreme ignorance about this period of cosmic history and the value of the COMAP- EoR measurement. We carry out the most detailed forecast to date of an intensity mapping cross correlation, and find that five out of the six models we consider yield signal to noise ratios (S/Ns) ≳ 20 for COMAP- EoR, with the brightest reaching a S/N above 400. We show that, for these models, COMAP- EoR can make a detailed measurement of the cosmic molecular gas history from z ∼ 2â€"8, as well as probe the population of faint, star-forming galaxies predicted by these models to be undetectable by traditional surveys. We show that, for the single model that does not predict numerous faint emitters, a COMAP- EoR -type measurement is required to rule out their existence. We briefly explore prospects for a third-generation Expanded Reionization Array (COMAP- ERA) capable of detecting the faintest models and characterizing the brightest signals in extreme detail. [ABSTRACT FROM AUTHOR]

The CO Mapping Array Project (COMAP) aims to use line-intensity mapping of carbon monoxide (CO) to trace the distribution and global properties of galaxies over cosmic time, back to the Epoch of Reionization (EoR). To validate the technologies and techniques needed for this goal, a Pathfinder instrument has been constructed and fielded. Sensitive to CO(1â€"0) emission from z = 2.4â€"3.4 and a fainter contribution from CO(2â€"1) at z = 6â€"8, the Pathfinder is surveying 12 deg2 in a 5 yr observing campaign to detect the CO signal from z ∼ 3. Using data from the first 13 months of observing, we estimate P CO(k) = âˆ'2.7 ± 1.7 Ă— 104 ÎĽ K2 Mpc3 on scales k = 0.051 âˆ'0.62 Mpcâˆ'1, the first direct three-dimensional constraint on the clustering component of the CO(1â€"0) power spectrum. Based on these observations alone, we obtain a constraint on the amplitude of the clustering component (the squared mean CO line temperature bias product) of Tb 2 < 49 ÎĽ K2, nearly an order-of-magnitude improvement on the previous best measurement. These constraints allow us to rule out two models from the literature. We forecast a detection of the power spectrum after 5 yr with signal-to-noise ratio (S/N) 9â€"17. Cross-correlation with an overlapping galaxy survey will yield a detection of the COâ€"galaxy power spectrum with S/N of 19. We are also conducting a 30 GHz survey of the Galactic plane and present a preliminary map. Looking to the future of COMAP, we examine the prospects for future phases of the experiment to detect and characterize the CO signal from the EoR. [ABSTRACT FROM AUTHOR]

Line intensity mapping (LIM) is a new technique for tracing the global properties of galaxies over cosmic time. Detection of the very faint signals from redshifted carbon monoxide (CO), a tracer of star formation, pushes the limits of what is feasible with a total-power instrument. The CO Mapping Project Pathfinder is a first-generation instrument aiming to prove the concept and develop the technology for future experiments, as well as delivering early science products. With 19 receiver channels in a hexagonal focal plane arrangement on a 10.4 m antenna and an instantaneous 26â€"34 GHz frequency range with 2 MHz resolution, it is ideally suited to measuring CO (J = 1â€"0) from z ∼ 3. In this paper we discuss strategies for designing and building the Pathfinder and the challenges that were encountered. The design of the instrument prioritized LIM requirements over those of ancillary science. After a couple of years of operation, the instrument is well understood, and the first year of data is already yielding useful science results. Experience with this Pathfinder will guide the design of the next generations of experiments. [ABSTRACT FROM AUTHOR]

The study of molecular gas is crucial for understanding star formation, feedback and the broader ecosystem of a galaxy as a whole. However, we have limited understanding of its physics and distribution in all but the nearest galaxies. We present a new technique for studying the composition and distribution ofmolecular gas in high-redshift galaxies inaccessible to existing methods. Our proposed approach is an extension of carbon monoxide intensity mapping methods, which have garnered significant experimental interest in recent years. These intensity mapping surveys target the 115 GHz 12CO (1-0) line, but also contain emission from the substantially fainter 110 GHz 13CO (1-0) transition. The method leverages the information contained in the 13CO line by cross-correlating pairs of frequency channels in an intensity mapping survey. Since 13CO is emitted from the same medium as the 12CO, but saturates at a much higher column density, this cross-correlation provides valuable information about both the gas density distribution and isotopologue ratio, inaccessible from the 12CO alone. Using a simple model of these molecular emission lines, we show that a future intensity mapping survey can constrain the abundance ratio of these two species and the fraction of emission from optically thick regions to order ~30 per cent. These measurements cannot be made by traditionalCOobservations, and consequently the proposed method will provide unique insight into the physics of star formation, feedback and galactic ecology at high redshifts. [ABSTRACT FROM AUTHOR]

We address the problem of line confusion in intensity-mapping surveys and explore the possibility to mitigate line foreground contamination by progressively masking the brightest pixels in the observed map. We consider experiments targeting CO(1-0) at z = 3, Ly a at z = 7, and C ii at z = 7, and use simulated intensity maps, which include both clustering and shot-noise components of the signal and possible foregrounds, in order to test the efficiency of our method. We find that for CO and Ly a, it is quite possible to remove most of the foreground contribution from the maps via only 1-3 per cent pixel masking. The C ii maps will be more difficult to clean, however, due to instrumental constraints and the high-intensity foreground contamination involved. While the masking procedure sacrifices much of the astrophysical information present in our maps, we demonstrate that useful cosmological information in the targeted lines can be successfully retrieved. [ABSTRACT FROM AUTHOR]

We present a study of the feasibility of an intensity-mapping survey targeting the 115 GHz CO(1–0) rotational transition at z ∼ 3. We consider four possible models and estimate the spatial and angular power spectra of CO fluctuations predicted by each of them. The frequency bandwidths of most proposed CO intensity mapping spectrographs are too small to use the Limber approximation to calculate the angular power spectrum, so we present an alternative method for calculating the angular power spectrum. The models we consider span two orders of magnitude in signal amplitude, so there is a significant amount of uncertainty in the theoretical predictions of this signal. We then consider a parametrized set of hypothetical spectrographs designed to measure this power spectrum and predict the signal-to-noise ratios (SNRs) expected under these models. With the spectrographs we consider we find that three of the four models give an SNR greater than 10 within one year of observation. We also study the effects on SNR of varying the parameters of the survey in order to demonstrate the importance of carefully considering survey parameters when planning such an experiment. [ABSTRACT FROM PUBLISHER]