Feasibility study of the Alcock-Paczyński cosmological test using cosmic voids

There are several ways to test the geometry and expansion of the universe. However, almost all of the cosmological tests are entangled with the evolution of galaxies and/or other effects. Here, we propose an implementation of the Alcock & Paczyński cosmological test (AP): an evaluation of the ratio of observed angular size to radial/redshift size. The main advantage of this test is that it does not depend on the evolution of galaxies, but only on the geometry of the universe. This method is particularly powerful for cosmic voids because they statistically exhibit spherical symmetry in real space. However, this fact is affected by redshift-space distortions due to peculiar motions of galaxies. Nevertheless, we can model the dynamics of voids using the anisotropic void-galaxy correlation function in redshift-space and the linear approach of gravitational collapse theory, so this effect can be disentangled. While the investigation of redshift-space distortions between pairs of galaxies has received enormous attention in the literature, comparable studies concerning voids remain rare, mainly because of the huge volume we need to cover to perform statistically significant tests. Fortunately, large and deep new surveys are coming soon (DESI, HETDEX, Euclid, eBOSS), so the aim of this work is to assess the feasibility of applying the AP test with voids and its dependence with deepness, using a high resolution and large volume simulation (comparable in size with the surveys just mentioned), the Millennium XXL.