title: Limits on the time variation of the electromagnetic fine-structure constant in the low energy limit from absorption lines in the spectra of distant quasars.
abstract: We present the results of a detailed many-multiplet analysis performed on a new sample of Mg ii systems observed in high quality quasar spectra obtained using the Very Large Telescope. The weighted mean value of the variation in alpha derived from our analysis over the redshift range 0.4</=z</=2.3 is Deltaalpha/alpha=(-0.06+/-0.06)x10(-5). The median redshift of our sample (z approximately 1.55) corresponds to a look-back time of 9.7 Gyr in the most favored cosmological model today. This gives a 3sigma limit, -2.5 x 10(-16)</=(Deltaalpha/alphaDeltat)</=+1.2 x 10(-16) yr(-1), for the time variation of alpha, that forms the strongest constraint obtained based on high redshift quasar absorption line systems.
authors.affiliation: IUCAA, Post Bag 4, Ganeshkhind, Pune 411 007, India.
authors.forename: R
authors.initials: R
authors.lastname: Srianand
authors.forename: H
authors.initials: H
authors.lastname: Chand
authors.forename: P
authors.initials: P
authors.lastname: Petitjean
authors.forename: B
authors.initials: B
authors.lastname: Aracil