CODEX Show Case 5

The complete science document (as it was prepared for Phase A , Feb. 2010) is available here in pdf format.

The values of many fundamental constants in physics have little if any theoretical explanations. Fundamental constants have thus long been speculated to vary in  space or time or both.  A discovery of such variations would be a revolutionary step and would almost certainly lead to the development of new Physics. The current evidence for small variations of the fine structure constant on cosmological timescales  from studies of QSO absorption spectra is intriguing but rather controversial. CODEX will take  tests of the stability of fundamental constants to largely improved new limits.

Figure 9.
Results of Murphy et al. (2004, Lecture Notes Phys., 648, 131) from 143 absorption systems obtained with the HIRES spectrograph at Keck. The authors claim the detection of a variability of the fine structure constant  with 5-sigma significance,  Delta(alpha)/alpha = -5.7 ± 1.1x10-6 
Figure 10.


Expected wavelength accuracy with CODEX at the E-ELT for a single Gaussian absorption line with a Doppler parameter = 2 km/s as a function of the exposure time for QSOs with magnitudes of = 16 (lower red curve) and V = 17 (upper blue curve).