Colloquium: Does the fine-structure constant vary across the sky?
KC-159, W&N-building, De Boelelaan 1081, VU University, Amsterdam
Colloquium:Does the fine-structure constant vary across the sky?
Michael Murphy, Swinburne University of Technology, Centre for Astrophysics & Supercomputing, Hawthorn, Victoria, Australia
Does the fine-structure constant vary across the sky?
Previous observations of quasar spectra from the Keck telescope (Hawaii) suggested a time variation of the fine-structure constant, alpha. We have now completed a new study using a large sample of quasar spectra from the Very Large Telescope (VLT; Chile). When the two datasets are analysed together, >4-sigma evidence for a variation of alpha across the sky emerges. Further, the dipole directions derived from each telescope independently are aligned on the sky, as are those derived from low- and high-redshift subsamples of the combined dataset. If this effect is not real, it requires a complicated combination of systematic effect to explain it. After presenting the evidence for this "alpha dipole", I will discuss current attempts to refute/confirm it.