# A new method of testing the gravitational redshift effect with radio interferometers

## TL;DR

This paper introduces a novel radio interferometry method to measure gravitational redshift effects with high precision, effectively canceling out classical Doppler effects and accounting for other influences.

## Contribution

The paper presents a new interferometric technique that enhances the measurement accuracy of gravitational redshift by eliminating dominant Doppler contributions.

## Key findings

- Residual gravitational redshift can be measured with ~10^{-3} precision using RadioAstron.
- Future space interferometers could achieve measurement precision up to 10^{-5}.
- Method effectively cancels classical Doppler effects in gravitational redshift measurements.

## Abstract

We propose a new method to measure gravitational redshift effect using simultaneous interferometric observations of a distant radio source to synchronize clocks. The first order by $v/c$ contribution to the signal (the classical Doppler effect) is automatically canceled in our setup. When other contributions from the velocities of the clocks, clock imperfection and atmosphere are properly taken into account, the residual gravitational redshift can be measured with the relative precision of $\sim 10^{-3}$ for RadioAstron space-to-ground interferometer or with precision up to few $10^{-5}$ with the next generation of space radio interferometers.