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28 September 2021
  » arxiv » astro-ph/0101519

 Article overview

Improved constraints on possible variation of physical constants from H I 21cm and molecular QSO absorption lines
M. T. Murphy ; J. K. Webb ; V. V. Flambaum ; M. J. Drinkwater ; F. Combes ; T. Wiklind ;
Date 29 Dec 2000
Journal Mon.Not.Roy.Astron.Soc. 327 (2001) 1244
Subject astro-ph
AffiliationUNSW), J. K. Webb (UNSW), V. V. Flambaum (UNSW), M. J. Drinkwater (UMelb), F. Combes (Paris Obs.), T. Wiklind (OSO
AbstractQSO absorption spectra provide an extremely useful probe of possible cosmological variation in various physical constants. Comparison of H I 21cm absorption with corresponding molecular (rotational) absorption spectra allows us to constrain variation in y=alpha^2*g_p where alpha 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 dy/y at absorption redshifts of z=0.2467 and 0.6847 by simultaneous fitting of the H I 21cm and molecular lines. We find dy/y=(-0.20 +/- 0.44)*10^{-5} and dy/y=(-0.16 +/- 0.54)*10^{-5} respectively, indicating an insignificantly smaller y in the past. We compare our results with other recent constraints from the same two QSOs (Drinkwater et al. 1998; Carilli et al. 2000) and with our recent optical constraints which indicated a smaller alpha at higher redshifts.
Source arXiv, astro-ph/0101519
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