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EP: Fachverband Extraterrestrische Physik
EP 5: Astrophysics
EP 5.1: Talk
Wednesday, February 28, 2024, 14:15–14:30, ELP 1: HS 1.22
Astrophysical test of the equality of active and passive gravitational mass — •Claus Lämmerzahl and Eva Hackmann — ZARM, University of Bremen, Gemany
Each body possesses three types of a mass: the inertial mass, the passive gravitational mass (or weight), and the active gravitational mass (or gravitating mass). The equivalence of inertial and passive gravitational mass, also known as the Weak Equivalence Principle, has been confirmed at the level of 10−15 by the recent space mission MICROSCOPE.
The precision of tests of the equivalence of the active and passive gravitational mass scales with the strength of the gravitational field created by the participating masses. This makes laboratory tests very difficult yielding an estimate of the order 10−6, only. On the other hand, one can show that gravitationally bound astrophysical masses with their strong gravitational fields are not suited for corresponding tests. The only viable situation for an astrophysical test is a solid body composed of different masses of different composition moving in a gravitational field of another body. Our Moon with non-concentric iron and aluminum dominated parts provides such an example.
In the presentation we will provide the theoretical background and describe our data analysis of more than 50 years of Lunar Laser Ranging. As a consequence, with Lunar Laser Ranging, any non-equivalence of the active and passive gravitational mass is now bound by 4 · 10−14. In addition, new planned laboratory tests will be shortly described.
Keywords: equivalence principle; Lunar Laser Ranging