Extreme star-forming galaxies at high redshift can also be used as a standard candle. This is possible due to the use of a well-known empirical correlation between the velocity dispersion, metallicity and luminosity in Hβ as a distance indicator. This relation has been calibrated using  nearby HII galaxies and provides distance measurements with a typical error of 10%. While the reliability of this method has already been demonstrated for a sample of 15 star-forming galaxies at z>2, GOYA will provide a sample of hundreds of these high-redshift galaxies suitable for distance measurements. This large sample will allow to constrain values of the cosmological parameters ΩM and ΩΛ, independently from any possible systematics affecting other methods, including CMB and SNIa.

 

In addition, GOYA will allow a direct measure of any time evolution of the fine structure constant, α. Such evolution is indeed predicted by some dark energy scenarios. α can be measured from the wavelengths of the two [OIII] emission lines at 4959 and 5007 Å. GOYA will allow very precise measurements of the [OIII] wavelengths by using the NIR OH lines to ensure any systematics and random errors are <0.001 Å differential between the two [OIII] lines.