Cosmic Voids: Fundamental Physics from the Unexplored Universe

• Applicant: Dr. Nico Hamaus
• Subject Area: Astrophysics and Astronomy
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439631294

Astronomers have now mapped out significant fractions of the observable Universe to unprecedented detail, enabling the field of cosmology to become a high-precision science. The standard model of cosmology provides an extremely successful framework to interpret various observables on a common ground, such as the large-scale distribution of galaxies, the abundance of galaxy clusters, the distances to supernovae, or the cosmic microwave background. Yet, all of these observables only make up for a minute fraction of the total matter and energy budget, and have revealed the Universe to be mostly composed of dark components whose origin remains unknown. Dark energy is held responsible for its observed accelerated expansion, acting like a repulsive form of gravity. It poses one of the biggest open questions of our time, encouraging scientists to search for gaps in Einstein’s theory of General Relativity. Dark matter controls the build-up of cosmic structures and bends the paths of light rays on their way through space-time, it is expected to consist of particles that yet have neither been produced, nor detected in any lab experiment on earth.Cosmic voids - vast regions of relatively empty space that prevail throughout the Universe - provide new clues to these long-standing enigmas. Recent breakthroughs in research have demonstrated voids to contain a wealth of cosmological information. They represent the most dark energy dominated structures in the Universe and hence genuine laboratories to study this mysterious substance. At the same time they offer novel ways to probe the nature of gravity, as the consequences of modifications to General Relativity are most striking in their interiors. Moreover, voids are sensitive to the properties of dark matter and neutrinos, elusive particles that permeate the cosmos. Yet, they have largely been neglected as a cosmological probe by the scientific community to date. Thanks to enormous efforts in survey design, the current generation of redshift surveys for the first time allows a rigorous statistical treatment of cosmic voids, establishing a new era for the exploration of fundamental physics. I plan to unveil this potential with dedicated efforts to analyze voids in state-of-the-art simulations and extensive data sets from large-scale structure surveys. This will furnish competitive and complementary constraints on our current models of cosmology, gravity, and particle physics, with a high potential for unexpected discoveries originating from a yet unexplored realm of the Universe.

• DFG Programme: Research Grants