Insights from probability distribution functions of intensity maps
  In the next few years, intensity-mapping surveys that target lines such as
CO, Ly$\alpha$, and CII stand to provide powerful probes of high-redshift
astrophysics. However, these line emissions are highly non-Gaussian, and so the
typical power-spectrum methods used to study these maps will leave out a
significant amount of information. We propose a new statistic, the probability
distribution of voxel intensities, which can access this extra information.
Using a model of a CO intensity map at $z\sim3$ as an example, we demonstrate
that this voxel intensity distribution (VID) provides substantial constraining
power beyond what is obtainable from the power spectrum alone. We find that a
future survey similar to the planned COMAP Full experiment could constrain the
CO luminosity function to order $\sim10\%$. We also explore the effects of
contamination from continuum emission, interloper lines, and gravitational
lensing on our constraints and find that the VID statistic retains significant
constraining power even in pessimistic scenarios.
