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Determining cosmological parameters with cosmic voids

Cosmic voids are prominent structures of the universe, so they can be used as cosmological tools. In particular, a well studied cosmological test is the Alcock-PaczyĆski effect using the void-galaxy cross correlation function. In this opportunity, I will present a version of this test in which we fit the matter-density (assuming a flat space), void-bias and velocity-dispersion parameters. Particularly, I will focus on the issues of the fitting process, such us the effect of each parameter on the correlation function and the behaviour of the likelihood confidence regions with the redshift. In order to accomplish this, we used the Millennium XXL simulation at different redshifts. This will shed light about the performance of the test applied on the new generation of galaxies surveys.