Probing Dark Energy with Baryonic Acoustic Oscillations at High   Redshifts
  The phases as well as the amplitudes of baryonic acoustic oscillations can be extracted out of a galaxy power spectrum and used as a standard ruler in a cosmological test. A non-oscillating phenomenological fitting function is used to extract the oscillatory part of the galaxy power spectrum and to disentangle phase information from amplitude information. The method (FITEX) is tested with simulated data of the Hubble Volume Simulation to include redshift space effects, non-linear structure growth and biasing. A cosmological test is introduced, which compares the extracted oscillations against a theoretical model template to derive constraints on the $w$ parameter.   The phenomenological fitting function is found to model the various distortions of the galaxy power spectrum to the sub-percent level. The various distortions only boost the amplitude of the oscillations. The theoretical template is accurate enough to test for small deviations in the phases of the oscillations, resulting from different $w$ values. A cosmological test, using the baryonic acoustic oscillations as a standard ruler, is able to constrain $w$ in a robust way. 
Ralf S. Koehler, Peter Schuecker and Karl Gebhardt