Universal profile for cosmic birefringence tomography with radio galaxies

Understand

We propose a new method to tomographically probe cosmic birefringence using radio galaxies.

• We show that the redshift evolution of the cosmic birefringence angle induced by a slow-rolling pseudoscalar field, which is a candidate for dynamical dark energy, is independent of the detailed model of the pseudoscalor field.
• This universal profile evolves predominantly at $z\lesssim10$.
• In contrast, if the origin is a dark matter-like pseudscalor field, the resulting birefringence angle tends to be negligible in the low-redshift regime.