1997/11/17 by F. Combes, Combes, F., T. Wiklind +1
Physics and Astronomy · #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #Cosmology and Gravitation Theories #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9711184
8 pages, 4 figures, to be published in Proceedings of Green-Bank Conference, 9-11 October 1997, ed. C. Carilli
arxiv created 1997/11/17 · openalex publication_date 1997/11/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Some recent results are presented about high redshift molecular absorption lines, namely about chemical abundances of elements, and in particular of water and molecular oxygen. Excitation temperatures of several molecules are found lower than the cosmic background temperature at the corresponding redshift z=0.88582 in PKS1830-211, and interpretations are proposed. The radio flux monitoring of the two gravitational images of PKS1830-211 is presented over almost two years, but precise calibration is still preventing the determination of the time-delay without ambiguity. The high spectral resolution of radio observations allows to put constraints on the variation of the fine-structure constant over a large fraction of the Hubble time.