Leveraging cross-correlations and linear covariance-based filtering for line-intensity map reconstructions at linear scales

We explore the possible application of linear covariance-based (LCB) filtering to line-intensity mapping (LIM) signal reconstructions. Originally introduced for reconstruction integrated Sachs-Wolfe effect in cosmic microwave background, LCB filter is an optimal map estimator that extends simple Wiener by leveraging external correlated data. Given a detectable strong LIM-galaxy or LIM-LIM cross power spectrum, we show recovery high-redshift, large-scale fluctuations---even presence bright interloper emission---in simulations futuristic [C ii] LIM survey as well simulated future iterations CO Mapping Array Project. With sufficient galaxy abundances low noise, normalized cross-correlation between and true reaches 70%--90% on large, comoving scales corresponding $k\ensuremath{\sim}0.1\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$. This suggests use such reconstructions astrophysical cosmological contexts require identifying locations line emissivity peaks voids, although clear shortcomings exist smaller scales. The successful highlights importance cross-correlations studies reionizing reionized high-redshift universe with other structure surveys.