Searching for chameleon-like scalar fields with the ammonia method

Abstract

Context. In our previous work we found a statistically significant offset ΔV ≈ 27 m s-1 between the radial velocities of the HC3N J = 2−1 and NH3 (J,K) = (1,1) transitions observed in molecular cores from the Milky Way. This may indicate that the electron-to-proton mass ratio, μ ≡ me/mp, increases by ~3 × 10-8 when measured under interstellar conditions with matter densities of more than 10 orders of magnitude lower than with laboratory (terrestrial) environments.