Probing helium reionization with kinetic Sunyaev-Zel'dovich tomography

Reionization of helium is expected to occur at redshifts z -3 and have important consequences for quasar populations, galaxy formation, and the morphology of the intergalactic medium, but there is little known empirically about the process. Here we show that kinetic Sunyaev-Zel'dovich tomography, based on the combination of cosmic microwave background (CMB) measurements and galaxy surveys, can be used to infer the primordial helium abundance as well as the time and duration of helium reionization. We find a high-significance detection at-10 sigma can be expected from Vera Rubin Observatory and CMB-S4 in the near future. A more robust characterization of helium reionization will require next-generation experiments like MegaMapper (a proposed successor to the Dark Energy Spectroscopic Instrument) and CMB-HD.

Automated summary

This paper demonstrates a method for inferring the primordial helium abundance and the time and duration of helium reionization through kinetic Sunyaev-Zel'dovich tomography, which combines cosmic microwave background (CMB) measurements and galaxy surveys. It is expected that a high-significance detection at -10 sigma could be achieved in the near future using the Vera Rubin Observatory and CMB-S4. However, a more robust characterization of helium reionization will require next-generation experiments like MegaMapper and CMB-HD.