Open AccessImproved constraints on possible variation of physical constants from H i 21‐cm and molecular QSO absorption lines
Author(s) -
Murphy M.T.,
Webb J.K.,
Flambaum V.V.,
Drinkwater M.J.,
Combes F.,
Wiklind T.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04843.x
Subject(s) - qsos , physics , quasar , astrophysics , redshift , spectral line , absorption (acoustics) , fine structure constant , absorption spectroscopy , variation (astronomy) , astronomy , galaxy , optics , quantum mechanics , electron
Quasar (QSO) absorption spectra provide an extremely useful probe of possible cosmological variation in various physical constants. Comparison of H i 21‐cm absorption with corresponding molecular (rotational) absorption spectra allows us to constrain variation in , where α is the fine‐structure constant and g p is the proton g ‐factor. We analyse spectra of two QSOs, PKS 1413+135 and TXS 0218+357, and derive values of at absorption redshifts of and 0.6847 by simultaneous fitting of the H i 21‐cm and molecular lines. We find and respectively, indicating an insignificantly smaller y in the past. We compare our results with other constraints from the same two QSOs given recently by Drinkwater et al. and Carilli et al., and with our recent optical constraints, which indicated a smaller α at higher redshifts.