Search for Varying Constants of Nature from Astronomical Observation of Molecules

2017/09/27 by W. Ubachs, Wim Ubachs
Earth and Planetary Sciences · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Context (archaeology) #Diatomic molecule #Dimensionless quantity #Galaxy #Hubble's law #Molecule #Physics #Quantum mechanics #Redshift #Spectral line #Spectrograph #astro-ph.CO

paper · pdf · doi:10.1007/s11214-017-0432-y

Contribution to Workshop "High Performance Clocks in Space" at the International Space Science Institute, Bern 2015

arxiv created 2017/09/27 · openalex publication_date 2017/11/30 · arxiv updated 2017/12/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

The status of searches for possible variation in the constants of nature from astronomical observation of molecules is reviewed, focusing on the dimensionless constant representing the proton-electron mass ratio μ =m_p/m_e . The optical detection of H2 and CO molecules with large ground-based telescopes (as the ESO-VLT and the Keck telescopes), as well as the detection of H2 with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope is discussed in the context of varying constants, and in connection to different theoretical scenarios. Radio astronomy provides an alternative search strategy bearing the advantage that molecules as NH3 (ammonia) and CH3OH (methanol) can be used, which are much more sensitive to a varying μ than diatomic molecules. Current constraints are |Δ μ /μ | < 5 × 10^-6 for redshift z=2.0--4.2 , corresponding to look-back times of 10–12.5 Gyrs, and |Δ μ / μ | < 1.5 × 10^-7 for z=0.88 , corresponding to half the age of the Universe (both at 3σ statistical significance). Existing bottlenecks and prospects for future improvement with novel instrumentation are discussed.

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