Research
My work is theoretical and phenomenological: I build models of how cosmic rays are accelerated and transported, and confront them with the data returned by direct-detection experiments, air-shower arrays and gamma-ray and neutrino observatories. Four themes organise most of what I do. A curated list of papers is on the publications page; the codes I maintain are listed there as well.
Galactic Cosmic Rays: transport and phenomenology
How cosmic rays propagate through the Galaxy, and what the spectra we measure at Earth tell us about their sources. My main interest is in non-linear transport, where the particles are not passive tracers of a fixed magnetic turbulence but generate the waves that scatter them. This self-confinement picture connects the shape of the observed spectra, the size of the diffusive halo, and the anisotropy — quantities usually treated independently. On the phenomenological side I work on the interpretation of precision data from AMS-02, and on the origin of the knee.
Recent work:
- A Population View of the Cosmic-Ray Knee: The Role of Variance in Supernova Maximum Rigidities, Physics and the Cosmos 1, 8 (2026) [arXiv]
- Transition from Diffusion to Drift-Dominated Cosmic Ray Transport and the Origin of the Knee [arXiv]
- Deciphering the Electron Spectral Hardening in AMS-02, Astronomy 4, 4 (2025) [arXiv]
- The environment of TeV halo progenitors, Astronomy & Astrophysics 706, A140 (2026) [arXiv]
Ultra-High-Energy Cosmic Rays: composition
At the highest energies the key observable is not the spectrum alone but the mass composition, inferred indirectly from the depth of shower maximum. I work on both ends of that inference: the air-shower parametrisations that turn measurements into statements about composition, and the propagation of nuclei through intergalactic magnetic fields, where self-generated turbulence and the structure of the magnetised cosmic web can reshape both spectrum and composition before the particles reach us. I am a member of the Pierre Auger Collaboration.
Recent work:
- Updated air-shower Xmax moment parametrizations for UHECR composition with latest hadronic interaction models, Astroparticle Physics 179, 103239 (2026) [arXiv]
- Self-confinement of ultra-high-energy nuclei in cosmic filaments: implications for the UHECR spectrum and composition [arXiv]
- The Impact of the Magnetised Cosmic Web on Ultra High Energy Cosmic Ray Propagation [arXiv]
- Excitation of the nonresonant streaming instability around sources of ultrahigh-energy cosmic rays, Astronomy & Astrophysics 707, A19 (2026) [arXiv]
Gamma and neutrino astrophysics: diffuse emissions
Cosmic rays are only directly observable near Earth, but the gamma rays and neutrinos they produce in interactions with interstellar gas map their distribution across the whole Galaxy. Diffuse emissions are therefore a transport diagnostic, and a demanding consistency test: any model of Galactic propagation must reproduce the spectra measured locally and the diffuse sky seen by Fermi-LAT, LHAASO and IceCube simultaneously. Much of my recent work is about whether the current picture passes that test.
Recent work:
- The origin of very high-energy diffuse γ-ray emission: The case for galactic source cocoons, Astronomy & Astrophysics 698, L18 (2025) [arXiv]
- LHAASO protons versus LHAASO diffuse gamma-rays: a consistency check, MNRAS Letters 543, L20 (2025) [arXiv]
- Scrutinizing the cosmogenic origin of the KM3-230213A event: A Multimessenger Perspective [arXiv]
Physics beyond the Standard Model in Astroparticle
Astrophysical environments reach energies and densities no laboratory can, which makes them sensitive probes of new physics. I use cosmic-ray and neutrino observations to constrain super-heavy dark matter, primordial black holes and axion-like particles — work that runs through my earlier interest in how energy injected by exotic particles affects the early Universe.
Recent work: