Cosmic Voids: Fundamental Physics from the Unexplored Universe

• Applicant: Dr. Nico Hamaus
• Subject Area: Astrophysics and Astronomy
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439631294

• Final Report Year: 2025

Final Report Abstract

The ΛCDM model is quite successful in the phenomenological description of the evolution of our Universe and the structures within, even though it relies on two as of yet unknown forms of matter and energy. According to this model, most of the matter in our Universe is in the form of cold dark matter (CDM) and visible structures made up of baryonic matter contain significantly less mass than CDM. The other unknown quantity that drives the late-time accelerated expansion of our Universe is referred to as dark energy. A cosmological constant Λ for this type of energy is so far consistent with observations. The most over-dense structures in our Universe have been studied extensively and through their use in observations the ΛCDM model was built. In contrast, the study of the largest and most under-dense regions of the cosmic web, known as cosmic voids, emerged only in recent years. While their use as cosmological probes is already well established, there is still a vast space to explore various aspects of their structure and dynamics, as well as to test the validity of predictions from linear theory in these under-dense environments. The subject of this project is to test both of these aspects by using state-of-the-art hydrodynamical N-body simulations. The detailed study of voids is not only interesting in its own right, but our results can additionally help in improving current methods employed in cosmological tests with voids, as well as maximize their use across both time and scale.

Publications

• Unique characteristics of voids in a complex universe. Dissertation, LMU München: Faculty of Physics
  Nico Schuster
  
• Why cosmic voids matter: nonlinear structure & linear dynamics. Journal of Cosmology and Astroparticle Physics, 2023(05), 031.
  Schuster, Nico; Hamaus, Nico; Dolag, Klaus & Weller, Jochen
  
• Why cosmic voids matter: mitigation of baryonic physics. Journal of Cosmology and Astroparticle Physics, 2024(08), 065.
  Schuster, Nico; Hamaus, Nico; Dolag, Klaus & Weller, Jochen
  
• Cosmological inference with cosmic voids and neural network emulators. Astronomy & Astrophysics, 705, A62.
  Lehman, Kai; Schuster, Nico; Lucie-Smith, Luisa; Hamaus, Nico; Davies, Christopher T. & Dolag, Klaus