Geometric Distortion of the Correlation function of Lyman-break Galaxies

Abstract

The number of galaxies with measured redshifts > 1 is at present rapidly increasing, allowing for measurements of their correlation function. The correlations function is measured in redshift space, as a function of angular separation and velocity difference. The relation between angle and velocity difference depends on the cosmological model through the factor H(z)D(z), where H(z) is the Hubble parameter and D(z) is the angular diameter distance. Therefore, the cosmological model can be constrained by measuring this factor from the shape of the contours of the redshift space correlation function, if the effect of peculiar velocities can be taken into account. Here, we investigate this method applied to the high redshift Lyman-break galaxies. The high bias factor of this galaxy population should suppress peculiar velocity effects, leaving the cosmological distortion as the main contribution to the anisotropy of the correlation function. We estimate the shot noise and cosmic variance errors using linear theory. A field size of at least 0.2 square degrees is required to distinguish the Einstein-de Sitter model from the flat Lambda=0.7 model, if 1.25 Lyman-break galaxies are measured per square arc minute. With a field of 1 square degrees, the cosmological constant can be measured to 20 % accuracy if it is large (> 0.5). Other equations of state for a scalar field can also be constrained.