Cosmic voids

A major research theme has been the study of cosmic voids — vast, under-dense regions occupying most of the volume of the Universe. When I began working on my Master’s thesis, the community had theoretically demonstrated that the statistical properties of these structures could be exploited to constrain dark energy and test theories of gravity, but the theoretical models describing the void size distribution consistently failed to predict both simulated and observed data.

My work has paved the way for the cosmological exploitation of the void size function when voids are identified in any distribution of tracers, including real data catalogues. In Ronconi & Marulli (2017) we presented an algorithm that redefines void ridges and, consequently, their radii; I implemented it inside CosmoBolognaLib, a large set of open-source numerical libraries for cosmological calculations.

With this tool we then demonstrated that, as long as our specifications are accounted for, the size function is a viable approach for studying cosmology with cosmic voids. The result was further validated by its adoption as a fundamental tool in Key Projects within the Euclid Collaboration, used to forecast the cosmological constraining power of void statistics.

Currently: I am working with members of the Euclid Collaboration on void statistics in mock galaxy catalogues, and investigating a new theoretical model of the void distribution based on stochastic differential equations, together with Andrea Lapi at SISSA. A Ph.D. student has recently been selected to pursue this direction over the next three years under our supervision.

Key papers: Ronconi & Marulli 2017 · Ronconi et al. 2019 · Contarini, Ronconi et al. 2019 · Contarini et al. 2022

Software: CosmoBolognaLibCosmoBolognaLib