AMMONIA AS A TRACER OF FUNDAMENTAL CONSTANTS

摘要

Observing inversion lines of ammonia (NH3), complemented by rotational lines of NH3 and other molecular species, provides stringent constraints on potential variations of the proton-to-electron mass ratio, μ. While a limit of |Δμ|/μ ~ 10~(?6) is derived for a lookback time of 7 × 10~9 yr, nearby dark clouds might show a significant variation of order (2 ? 3) × 10~(?8), possibly being related to chameleon fields. The detection of radioloud quasars with strong molecular absorption lines at redshifts z > 1 as well as the identification of a larger sample of nearby molecular clouds with exceptionally narrow lines (ΔV < 0.2kms~(?1)) would be essential to improve present limits and to put the acquired results onto a firmer statistical basis.