Elucidating the dark: neutrinos and dark matter properties with Euclid and SKA

• Applicant: Professor Dr. Julien Lesgourgues
• Subject Area: Astrophysics and Astronomy
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568980474

The nature of dark matter and the properties of cosmic neutrinos remain two of the most critical questions in fundamental physics. Cosmological observations not only provide insights into the total mass of neutrinos and the abundance of dark matter but also offer the potential to uncover their microscopic properties, such as self-interactions, interactions with the Standard Model particles, the particle or wave nature of dark matter, and its thermal velocity. These properties leave distinct imprints on clustering properties of the cosmic large-scale structures (LSS), which can be probed by the observed distribution of individually-resolved galaxies in spectroscopic galaxy surveys and that of fluctuations in the aggregate light from galaxies or intergalactic medium in line intensity mapping surveys. Given the unprecedented volume and precision of upcoming galaxy surveys like Euclid, and future wide-field intensity mapping projects like SKA, there is renewed urgency to investigate the potential of LSS observations in revealing properties of the dark sector. However, the increasing precision and volume of forthcoming data also present challenges in ensuring that theoretical models and analysis tools keep pace in accuracy and efficiency. Our proposed research aims to develop a robust and efficient framework that incorporates a broad range of neutrino and dark matter models, assessing their effects on LSS statistics as measured by the power spectrum and bispectrum of galaxies or intensity maps. Specifically, we will generalize existing analytic methods—particularly the Effective Field Theory of Large-Scale Structure—to include the effects of massive neutrinos and non-standard dark matter. Leveraging the expertise of both principal investigators in modelling dark matter, neutrinos, and analyzing LSS observables, this framework builds on their recent efforts to develop the CLASS-Oneloop code, enabling comprehensive analysis of these datasets, individually and in combination.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partner: Azadeh Moradinezhad Dizgah, Ph.D.