Syllabus
High-Energy Astroparticle Physics – Theory (2026/2027)
Synopsis
High-energy astroparticle physics studies the most energetic particles in the Universe (cosmic rays, gamma rays and neutrinos) and the sources that produce them. This course develops the theory needed to interpret these observations. It follows one population of particles from the sources where they are accelerated, through the magnetized interstellar medium where they propagate, to the radiation they produce along the way.
The course has three parts:
- Radiative processes (lectures 1–4). How relativistic electrons and nuclei lose energy and radiate: synchrotron and inverse Compton emission, gamma-ray absorption, and hadronic interactions with gas and photons. These processes connect cosmic rays to the gamma rays and neutrinos we observe.
- Cosmic-ray transport (lectures 5–11). Why cosmic rays diffuse through the Galaxy. Starting from the basic properties of astrophysical plasmas, we derive the cosmic-ray transport equation and obtain the diffusion coefficient from the scattering of particles by magnetic turbulence. We then use them to interpret measurements of nuclei, electrons, positrons and antiprotons.
- Particle acceleration (lectures 12–15). How particles reach such high energies: the general requirements for acceleration, the physics of shock waves and supernova remnants, and diffusive shock acceleration with its observational tests.
Prerequisites
Classical electrodynamics, special relativity, statistical mechanics, and basic particle physics and astrophysics. No background in plasma physics is assumed: the plasma physics and magnetohydrodynamics needed in the course are introduced from scratch.
Exam
There are two lists of problems: one on radiative processes, one on transport and acceleration. Each student picks one problem from each list, solves both individually, and presents the solutions at the blackboard.
Lectures
15 lectures of 2 hours.
Part I – Radiative processes
- Lecture 1. Introduction and synchrotron radiation
- Cosmic rays, gamma rays and neutrinos: the multi-messenger view
- Course and exam organization
- Kinetic equation for particles with radiative losses
- The cooling break
- Lecture 2. Synchrotron radiation
- Synchrotron power from a single particle
- Relativistic aberration
- Synchrotron characteristic frequency
- Synchrotron radiation from a population of electrons