Spatial variation in the fine-structure constant -- new results from VLT/UVES

Understand

(abridged) We present a new analysis of a large sample of quasar absorption-line spectra obtained using UVES (the Ultraviolet and Visual Echelle Spectrograph) on the VLT (Very Large Telescope) in Chile.

• In the VLT sample (154 absorbers), we find evidence that alpha increases with increasing cosmological distance from Earth.
• However, as previously shown, the Keck sample (141 absorbers) provided evidence for a smaller alpha in the distant absorption clouds.
• Upon combining the samples an apparent variation of alpha across the sky emerges which is well represented by an angular dipole model pointing in the direction RA=(17.3 +/- 1.0) hr, dec.