A new probe of the high-redshift Universe: nulling CMB lensing with interloper-free "LIM-pair" lensing

Understand

Intermediate redshifts between galaxy surveys and the cosmic microwave background (CMB) remain unexplored territory.

• Line intensity mapping (LIM) offers a way to probe the $z\gtrsim 1$ Universe, including the epoch of reionization and the dark ages.
• Via exact nulling of the lensing kernel, we show that LIM lensing, in combination with galaxy (resp., CMB) lensing, can uniquely probe the $z\gtrsim 1$ (resp., pre-reionization) Universe.
• However, LIM foregrounds are a key hurdle to this futuristic technique.