Here we present a pilot study into whether elliptical galaxy counts alone , can place a useful constraint on the \Omega _ { M } - \Omega _ { \Lambda } -plane .
The elliptical galaxy counts are drawn from three surveys : The Millennium Galaxy Catalogue ( 16 > B _ { KPNO } > 20 ) , the B-band Parallel Survey ( 20 > B _ { AB } > 24 ) and the Hubble Deep Fields ( 23 > B _ { AB } > 28 ) .
The elliptical luminosity function used in the modeling was derived from a combination of the Millennium Galaxy Catalogue , the two-degree field galaxy redshift survey and the Sloan Digital Sky Survey ( M _ { * } ^ { E / S 0 } = -19.90 , \phi _ { * } ^ { E / S 0 } = 0.0019 Mpc ^ { -3 } and \alpha ^ { E / S 0 } = -0.75 for H _ { o } = 75 km/s/Mpc ) .
We adopt a benchmark model and tweak the various input parameters by their uncertainties to determine the impact upon the counts .
We find that if the faint-end slope of the elliptical galaxy luminosity function is known to \Delta \alpha < 0.1 , then over the magnitude range 16 < B < 23 the counts depend most critically upon the cosmology , and can be used to place a weak constraint on the \Omega _ { M } - \Omega _ { \Lambda } -plane .