Project F8:
"The high-energy frontier of indirect dark-matter searches"

Project Description

The nature of dark matter remains one of the most pressing open questions of modern physics. Since the mass of the dark-matter (DM) particle is unknown and collider experiments will not be able to probe the PeV regime in the foreseeable future, indirect searches with cosmic messengers are among the most sensitive ways to detect very heavy DM particles or to constrain their properties. So far, searches at these energies have been comparatively limited in scope. With new gamma-ray observatories for the TeV–PeV range on the horizon, namely the Cherenkov Telescope Array Observatory (CTAO), Dark100 and the Southern Wide-field Gamma-ray Observatory (SWGO), it is now timely to extend DM searches to the highest energies.
F8 is a new project in Phase 2. It builds on the work of project F5 in Phase 1, which combined cosmological and astroparticle-physics limits on DM and identified promising dwarf-galaxy targets in cosmological surveys. While F5 continues to search for Weakly Interacting Massive Particles (WIMPs) at the electroweak mass scale and for light axion-like particles, F8 targets ultra-heavy DM in the central region of the Milky Way and in dwarf galaxies identified by F5.
In Phase 2, we will develop a multi-instrument DM analysis pipeline spanning TeV to PeV energies, improve the observational sensitivity with tuned hadronic interaction models from projects F3 and F4, and combine our limits with those of F5 into a picture of DM constraints from sub-TeV energies to beyond 1 PeV, to address the following questions:

1. How sensitive can searches for ultra-heavy DM become when data from several TeV–PeV gamma-ray instruments are cross-calibrated and combined?
2. How well can the cosmic-ray proton background and the astrophysical foregrounds from the Galactic disc (A1) and from dwarf galaxies (A2) be characterized at the high-energy frontier?
3. Can we either discover ultra-heavy DM or set competitive limits on it, and combine them with lower-energy searches and with neutrino observations into global DM constraints from GeV to PeV?