Possible evidence for a variable fine structure constant from QSO absorption lines: Motivations, analysis and results

By M. Murphy, J. Webb, Victor V. Flambaum, V. Dzuba, C. Churchill, J. Xavier Prochaska, John D. Barrow, A. Wolfe. 2000

259 citations recorded by the source corpus.

An experimental search for variation in the fundamental coupling constants is strongly motivated by modern high-energy physics theories. Comparison of quasar absorption line spectra with laboratory spectra provides a sensitive probe for variability of the ne structure constant, , over cosmological time-scales. We have previously developed and applied a new method providing an order of magnitude gain in precision over previous optical astrophysical constraints. Here we extend that work by including new quasar spectra of damped Lyman- absorption systems. We also re-analyse our previous lower redshift data and conrm our initial results. The constraints on come from simultaneous tting of absorption lines of subsets of the following species: Mgi ,M gii, Alii ,A liii ,S iii ,C rii ,F eii ,N iii and Znii. We present a detailed description of our methods and results based on an analysis of 49 quasar absorption systems (towards 28 QSOs) covering the redshift range 0:5 <z <3:5. There is statistical evidence for a smaller at earlier epochs: = =( 0:720:18)10 5 . The new and original samples are independent but separately yield consistent and signicant non-zero values of =. We summarise the results of a thorough investigation of systematic eects published in a companion paper. The value we quote above is the raw value, not corrected for any of these systematic eects. The only signicant systematic eects so far identied, if removed from our data, would lead to a more signicant deviation of = from zero.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2a2d922d6327664094db6d89a7a41ea5f182aa98

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Citations in the corpus

Spatial variation in the fine-structure constant – new results from VLT/UVES (2012, background): “At higher redshifts, the effect on ∆α/α of isotopic abundance variations in other light species (e.g. Si) has been shown to be negligible (Murphy et al. 2001b).”
The fundamental constants and their variation: observational and theoretical status (2002, methodology): “A possible explanation is a variation of the isotopic ratio but the change of 26Mg/24Mg would need to be substantial to explain the result (Murphy et al., 2001b).”
Varying Constants, Gravitation and Cosmology (2010, methodology): “It was later confirmed in a re-analysis [376, 524] of the initial sample and by including new optical QSO data to reach 28 absorption systems with redshift z = 0.”
The Confrontation between General Relativity and Experiment (2005, background): “[269, 193] announced that measurements of absorption lines in Mg, Al, Si, Cr, Fe, Ni, and Zn in quasars in the redshift range 0.”
High‐precision wavelength calibration of astronomical spectrographs with laser frequency combs (2007, background): “Recent measurements ofα-variation using many absorption systems reach relative precisions of∼10−6 when comparing several transitions separated by up to∼5000 Å (e.g. Murphy et al. 2001; Murphy, Webb & Flambaum 2003).”
Further evidence for a variable fine-structure constant from Keck/HIRES QSO absorption spectra (2003, methodology): “The MM method constraints in the present work are more than an orderf magnitude more precise than the strongest AD method constrai t (obtained in Murphy et al. 2001c).”