Mon. Not. R. Astron. Soc., 487, 5175-5187 (2019/August-3)
Testing the weak equivalence principle by differential measurements of fundamental constants in the Magellanic Clouds.
LEVSHAKOV S.A., NG K.-W., HENKEL C., MOOKERJEA B., AGAFONOVA I.I., LIU S.-Y. and WANG W.-H.
Abstract (from CDS):
Non-standard fields are assumed to be responsible for phenomena attributed to dark energy and dark matter. Being coupled to ordinary matter, these fields modify the masses and/or charges of the elementary particles, thereby violating the weak equivalence principle. Thus, values of fundamental constants such as the proton-to-electron mass ratio, µ, and/or the fine structure constant, α, measured in different environment conditions can be used as probes for this coupling. Here we perform differential measurements of F = µα2 to test a non-standard coupling in the Magellanic Clouds-dwarf galaxies where the overall mass budget is dominated by dark matter. The analysis is based on [C I] and CO lines observed with the Herschel Space Observatory. Since these lines have different sensitivities to changes in µ and α, the combined α and µ variations can be evaluated through the radial velocity offsets, ΔV, between the CO and [C I] lines. Averaging over nine positions in the Magellanic Clouds, we obtain <ΔV> = -0.02 ± 0.07 km s–1, leading to |ΔF/F| < 2 x 10–7 (1σ), where ΔF/F = (Fobs - Flab)/Flab. However, for one position observed with five times higher spectral resolution we find ΔV = -0.05 ± 0.02 km s–1, resulting in ΔF/F = (-1.7 ± 0.7) x 10–7. Whether this offset is due to changes in the fundamental constants, due to chemical segregation in the emitting gas, or merely due to Doppler noise requires further investigations.
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
elementary particles - methods: observational - techniques: spectroscopic - Magellanic Clouds - dark matter - radio lines: ISM
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