In the first of the talk I will discuss the phenomenology of cosmic-ray diffusion in the Galaxy and the associated gamma-ray and neutrino emission. The aim is to understand how the combined study of local cosmic-ray spectra and diffuse emissions can help to unveil anomalies that may point towards either non-standard propagation scenarios (and new astrophysical phenomena in general), or new physics (for instance, particle dark matter annihilation/decay).

Since the discovery of the Higgs at the LHC, particle physics model building has been confronted with a severe conceptual challenge: the inferred values of the Higgs’ mass and self-coupling both appear to be fine-tuned. This not only poses the question what kind of new physics could explain such a behavior, but also undermines phenomenological efforts as acknowledging the possibility of fine-tuning oftentimes allows for the evasion of any experimental constraints. In the first half of my talk, I will review these fine-tunings and their implications more generally.

Active galactic nuclei (AGN) drive powerful, multiphase outflows into their host galaxies which are expected to play a key role in galaxy evolution. However, exactly how small-scale accretion disc winds couple to the ISM to drive these outflows remains an open question. In this talk, I will discuss our AGN in Clumpy DisCs (ACDC) simulations which feature a physically-motivated AGN wind model embedded in an idealised galaxy disc with a resolved ISM, manually distributed in a clumpy substructure.

The origins of the most energetic particles in the Universe have been a long-standing puzzle. In the quest to identify their sources, it is crucial to understand how these particles are accelerated, how they escape their production sites, and which paths they take on their journey to Earth. The multi-messenger framework has proven to be a powerful tool for exploring the Universe at these extreme energies. In this talk, I will focus on the triad of (ultra-)high-energy messengers: cosmic rays, neutrinos, and gamma rays.