Variation of fundamental parameters and dark energy. A principal   component approach
  We discuss methods based on Principal Component Analysis to constrain the dark energy equation of state using a combination of Type Ia supernovae at low redshift and spectroscopic measurements of varying fundamental couplings at higher redshifts. We discuss the performance of this method when future better-quality datasets are available, focusing on two forthcoming ESO spectrographs - ESPRESSO for the VLT and CODEX for the E-ELT - which include these measurements as a key part of their science cases. These can realize the prospect of a detailed characterization of dark energy properties almost all the way up to redshift 4. 
L. Amendola (ITP, U. Heidelberg), A. C. O. Leite (U. Porto), C. J. A.   P. Martins (CAUP, U. Porto), N. J. Nunes (ITP, U. He...
astro-ph.CO