1997/11/25 by M. J. Drinkwater, J. K. Webb, J. D. Barrow +1 · 92 citations
Physics and Astronomy · #Absorption (acoustics) #Absorption spectroscopy #Cosmology and Gravitation Theories #Fine-structure constant #Galaxies: Formation, Evolution, Phenomena #Lyman-alpha forest #Molecular absorption #Quasar #Radio Astronomy Observations and Technology #Redshift #Spectral line #Variation (astronomy) #astro-ph #gr-qc #hep-ph
paper · pdf · doi:10.1046/j.1365-8711.1998.2952457.x
published in Monthly Notices of the Royal Astronomical Society 295(2), 457-462 (Oxford University Press) · Latex document using mn style file; 6 pages and 3 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society
arxiv created 1997/11/25 · openalex publication_date 1998/04/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Recent detections of high-redshift absorption by both atomic hydrogen and molecular gas in the radio spectra of quasars have provided a powerful tool for measuring possible temporal and spatial variations of physical ‘constants’ in the universe. We compare the frequency of high-redshift hydrogen 21-cm absorption with that of associated molecular absorption in two quasars to place new (1σ) upper limits on any variation in y≡gpα2 (where α is the fine-structure constant, and gp is the proton g-factor of at redshifts z = 0.25 and 0.68. These quasars are separated by a comoving distance of 3000 Mpc (H0= 75 km s−1 Mpc−1 and q0). We also derive limits on the time rates of change and between the present epoch and z= 0.68. These limits are more than an order of magnitude smaller than previous results derived from high-redshift measurements.