Search for QCD Coupled Axion Dark Matter with Data from the MICROSCOPE Space Experiment

Axion dark matter coupled via QCD induces a nonzero differential acceleration between test masses of different composition. Tests of the equivalence principle, like the recent MICROSCOPE space mission, are sensitive to such a signal. We use the final released data of the MICROSCOPE experiment to search for this effect. We find no positive signal consistent with the dark matter model, and set upper limits on the axion-gluon coupling that improve existing laboratory bounds by up to 2 orders of magnitude for axion masses in the 10−17 to 10−13 eV range.