An Intensity Mapping Detection of Aggregate CO Line Emission at 3 mm

Understand

We present a detection of molecular gas emission at $z\sim1-5$ using the technique of line intensity mapping.

• We make use of a pair of 3 mm interferometric data sets, the first from the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS), and the second from a series of Atacama Compact Array (ACA) observations conducted between 2016 and 2018, targeting the COSMOS field.
• At 100 GHz, we measure non-zero power at 97.8% and 99.9% confidence in the ACA and ALMA data sets, respectively.
• In the joint result, we reject the zero-power hypothesis at 99.99% confidence, finding $\tilde{I}^{2}_{s}(\nu)=770\pm210\ \mu\textrm{K}^2\ \textrm{Hz}\ \textrm{sr}$.