Cosmology with kSZ: breaking the optical depth degeneracy with Fast Radio Bursts

Understand

The small-scale cosmic microwave background (CMB) is dominated by anisotropies from the kinematic Sunyaev-Zeldovich (kSZ) effect, and upcoming experiments will measure it very precisely, but the optical depth degeneracy limits the cosmological information that can be extracted.

• At the same time, fast radio bursts (FRBs) are an exciting new frontier for astrophysics, but their usefulness as cosmological probes is currently unclear.
• We show that FRBs are uniquely suited for breaking the kSZ optical depth degeneracy.
• This opens up new possibilities for constraining cosmology with the kSZ effect, and new cosmological applications for FRBs.