Astrometric test of the weak equivalence principle

TL;DR

This paper presents a novel astrometric method to test the weak equivalence principle using nearly 1,700 quasars observed in optical and radio wavelengths, providing the most robust bounds among photon-based tests.

Contribution

It introduces the first astrometric test of WEP using quasars across two wavelengths, surpassing previous methods based on time delay measurements.

Findings

Nearly 1,700 quasars used for testing WEP

Provides the most significant bounds on WEP violation among photon-based tests

Demonstrates the effectiveness of astrometry in fundamental physics tests

Abstract

Weak equivalence principle (WEP) is, for the first time, tested by astrometry on quasars in the sky measured in two wavelengths. Compared to previous WEP tests based on the Shapiro time delay of massless particles, this one has profound superiority that nearly 1,700 quasars with best measured positions commonly in the optical and radio bands are available. It ensures that, among the tests with photons, this one can give the most significantly robust bound on possible violation of WEP.