COLDz: Shape of the CO Luminosity Function at High Redshift and the Cold Gas History of the Universe

Understand

We report the first detailed measurement of the shape of the CO luminosity function at high redshift, based on $>$320 hr of the NSF's Karl G.

• Jansky Very Large Array (VLA) observations over an area of $\sim$60 arcmin$^2$ taken as part of the CO Luminosity Density at High Redshift (COLDz) survey.
• COLDz "blindly" selects galaxies based on their cold gas content through CO($J$=1$\to$0) emission at $z$$\sim$2-3 and CO($J$=2$\to$1) at $z$$\sim$5-7 down to a CO luminosity limit of log($L'_{\rm CO}$/K km s$^{-1}$ pc$^2$)$\simeq$9.5.
• We find that the characteristic luminosity and bright end of the CO luminosity function are substantially higher than predicted by semi-analytical models, but consistent with empirical estimates based on the infrared luminosity function at $z$$\sim$2.