A Computationally Efficient Approach for Calculating Galaxy Two-Point Correlations

摘要

We developed a modification to the calculation of the two-point correlationfunction commonly used in the analysis of large scale structure in cosmology.An estimator of the two-point correlation function is constructed bycontrasting the observed distribution of galaxies with that of a uniformlypopulated random catalog. Using the assumption that the distribution of randomgalaxies in redshift is independent of angular position allows us to replacepairwise combinatorics with fast integration over probability maps. The newmethod significantly reduces the computation time while simultaneouslyincreasing the precision of the calculation. It also allows to introducecosmological parameters only at the last and least computationally expensivestage, which is helpful when exploring various choices for these parameters.