Astrophysics & Particle Physics-APPC 2026

Dark Matter Annihilation and Decay are important research fields in particle astrophysics and cosmology, which try to explain the unseen matter that constitutes roughly 27% of the universe. In contrast to regular matter, dark matter neither absorbs nor reflects light nor emits it, hence only detected through the effects it has on gravity and the indirect evidence coming from the interactions of particles.Dark matter is thought to be at the core in galactic formation, cosmic structure growth, and the dynamic of galaxy clusters. Theoretical models propose that some of the dark matter particles, e.g., weakly interacting massive particles (WIMPs) or axions, can annihilate or decay into secondary particles detectable by gamma rays, neutrinos, or cosmic rays. Monitoring these signs is essential to comprehend the properties, distribution, and behavior of dark matter in the universe.Indirect detection experiments—space telescopes, ground-based gamma-ray observatories, and neutrino detectors—look for a sign of dark matter annihilation occurring in areas of high density, including the center of the galaxy or dwarf spheroidal galaxies. By studying these signals, particle properties such as mass, interaction cross-section, and lifetimes of decay are constrained.Experiments on dark matter annihilation and decay also constrain cosmological models by challenging predictions regarding cosmic structure growth and the impact of dark matter in the universe's evolution. By bringing observations together with simulations, researchers can investigate the role of dark matter in shaping the formation of galaxies, clusters of galaxies, and the cosmic web.Analyzing dark matter annihilation and decay not only pushes back the boundaries of fundamental physics but also unifies particle physics, astrophysics, and cosmology, providing an increased understanding of the unseen elements of the universe. Ongoing research in this area holds the promise of revealing the nature of dark matter and its decisive role in the universe, perhaps solving one of the greatest enigmas of contemporary science.