Cross-correlating Carbon Monoxide Line-intensity Maps with Spectroscopic and Photometric Galaxy Surveys

TL;DR

This paper explores the potential for detecting cross-correlation signals between CO line-intensity maps and galaxy surveys, emphasizing the importance of precise redshift measurements and source density for successful detection.

Contribution

It assesses the feasibility of cross-correlating CO intensity maps with galaxy surveys, highlighting the necessary redshift accuracy and source density for significant detection.

Findings

Spectroscopic redshift accuracy of <0.003 enhances detection prospects.

Source density of >10^{-4} sources/Mpc^3 is beneficial.

Future surveys could achieve these requirements for effective cross-correlation.

Abstract

Line-intensity mapping (LIM or IM) is an emerging field of observational work, with strong potential to fit into a larger effort to probe large-scale structure and small-scale astrophysical phenomena using multiple complementary tracers. Taking full advantage of such complementarity means, in part, undertaking line-intensity surveys with galaxy surveys in mind. We consider the potential for detection of a cross-correlation signal between COMAP and blind surveys based on photometric redshifts (as in COSMOS) or based on spectroscopic data (as with the HETDEX survey of Lyman-$\alpha$ emitters). We find that obtaining $\sigma_z/(1+z)\lesssim0.003$ accuracy in redshifts and $\gtrsim10^{-4}$ sources per Mpc$^3$ with spectroscopic redshift determination should enable a CO-galaxy cross spectrum detection significance at least twice that of the CO auto spectrum. Either a future targeted spectroscopic survey or a blind survey like HETDEX may be able to meet both of these requirements.