Radio Tests of GR

TL;DR

This paper reports on two radio-based tests of general relativity using VLBA observations, measuring solar deflection and Jupiter's retarded gravitational deflection, achieving high precision and addressing interpretative debates.

Contribution

It presents new high-precision measurements of gravitational deflection effects using VLBA, including the first measurement of Jupiter's retarded gravitational deflection.

Findings

PPN-gamma measured to 0.0003 accuracy

Jupiter's retarded deflection measured to 20% accuracy

Addresses controversy over retarded term interpretation

Abstract

Since VLBI techniques give microarcsecond position accuracy of celestial objects, tests of GR using radio sources as probes of a gravitational field have been made. We present the results from two recent tests using the VLBA: In 2005, the measurement of the classical solar deflection; and in 2002, the measurement of the retarded gravitational deflection associated with Jupiter. The deflection experiment measured PPN-gamma to an accuracy of 0.0003; the Jupiter experiment measured the retarded term to 20% accuracy. The controversy over the interpretation of the retarded term is summarized.