Cosmic voids detection without density measurements

Understand

Cosmic voids are effective cosmological probes to discriminate among competing world models.

• Their identification is generally based on density or geometry criteria that, because of their very nature, are prone to shot noise.
• We propose two void finders that are based on dynamical criterion to select voids in Lagrangian coordinates and minimise the impact of sparse sampling.
• The first approach exploits the Zel'dovich approximation to trace back in time the orbits of galaxies located in voids and their surroundings, the second uses the observed galaxy-galaxy correlation function to relax the objects' spatial distribution to homogeneity and isotropy.