The Use of Nonparametric Methods of Mathematical Statistics to Search for Cosmic Strings

Abstract

A part of the celestial sphere which has a cosmic string candidate (CSc-1 field) according to the radio data on cosmic microwave background anisotropy is statistically investigated to further substantiate this candidate. Cosmic strings are 1D cosmological-scale objects that can manifest themselves in particular as gravitational lenses with characteristic features. The problem of statistical comparison of the density distribution of gravitational-lens pairs of sources (galaxies) in the fields without cosmic strings with the distribution of similar pairs in the CSc-1 field is solved. Nonparametric rank tests are used to handle small samples under an unknown distribution law. The limits of applicability of the test are discussed. The revealed difference between the two distributions serves as an additional argument in favor of the presence of a string in the CSc-1 field. The discovery of cosmic strings would serve as a unique observational test of modern cosmological theories, including multidimensional models.