Constraining the expansion history and early dark energy with line intensity mapping

We consider the potential for line intensity mapping (IM) experiments to measure the baryon acoustic oscillations (BAO) from 3<z<6. This would constrain the expansion history in a redshift range that is currently unexplored. We calculate the map depths that future IM experiments targeting the CO (1-0) rotational transition line and CII ionized carbon fine-structure line would need to achieve in order to measure the BAO. We find that near-future IM experiments could constrain the BAO scale to 5% or better depending on CO/CII model amplitude. This measurement is at a precision that could make competitive constraints on models of early dark energy.