Faint Galaxy Number-Counts
Observers studying the cosmology and evolutionary history of our Universe through the statistical properties of “normal” galaxies have four main tools at their disposal. (1) The number-redshift relation. Although a very powerful diagnostic, spectroscopic surveys are currently limited to B < 24m and significantly incomplete in the range, 23m < B < 24m. (2) Galaxy number-magnitude counts. Although by themselves, they cannot constrain models as tightly as spectroscopy, they can be measured ~ 4m fainter, where cosmological effects are expected to be significant. (3) Galaxy colours over a wide wavelength range, which provide additional constraints. (4) The dependence of galaxy clustering with magnitude. ω(θ) can be measured to the limit of the counts.
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