Searching for Dark Matter with Imaging Atmospheric Cherenkov Telescopes

This book provides a comprehensive review of the methodologies and searches for dark matter (DM) annihilation signals using very-high-energy gamma rays (VHE, E > 100 GeV), utilizing data from current Imaging Atmospheric Cherenkov Telescopes (IACTs) in the pre-Cherenkov Telescope Array (CTA) era. It presents the state-of-the-art statistical analysis methods and theoretical models related to TeV DM, applied to data from the H.E.S.S. telescope array, which is currently the most sensitive IACT array for observing the Galactic Center (GC), where the brightest DM annihilation signals are expected.

The authors delve into the astrophysics of VHE gamma-ray production through cosmic ray acceleration. They explain the Imaging Atmospheric Cherenkov technique, describe the H.E.S.S. array, and discuss possibilities for DM annihilation-induced gamma-ray spectra and DM distribution profiles. By employing advanced statistical methods, they search for weak signals in the GC region using the H.E.S.S. Inner Galaxy Survey dataset and address systematic uncertainties. The authors present and debate the most constraining results on TeV dark matter models.

Finally, this book presents the sensitivity of current IACTs to DM annihilation signals using IGS mock datasets, accounting for systematic and instrumental uncertainties. Detection prospects for canonical TeV DM models, such as the Wino, Higgsino, and quintuplet, are discussed. Sensitivity benchmarks on indirect DM searches with IACTs using H.E.S.S. as an example are provided, setting the stage for future developments in the CTA era.
It serves as a consolidated resource for graduate students and researchers, presenting methodologies that could lead to significant advancements in the quest to understand dark matter.

Alessandro Montanari worked in the H.E.S.S. Collaboration at the Irfu/DPhP institute in CEA-Saclay (France) during his Ph.D. studies and the Landessternwarte institute at ZAH, Heidelberg University (Germany) for a Post-doctoral position. He analyzed observational datasets from the H.E.S.S. array, which consists of 5 Imaging Atmospheric Cherenkov Telescopes (IACTs), to obtain constraints on Dark Matter (DM) models and Fermi Bubbles (FBs) emission. He published results on DM in Phys. Rev. Lett. 129, 111101 (2022) and on FBs in PoS (ICRC2021) 791. He also searched for DM towards unidentified Fermi-LAT objects (UFOs) and published results in Astrophys. J. 918, 17 (2021). He contributed to presenting a comprehensive picture of the detection prospects with IACTs for specific particle DM model realizations in Phys. Rev. D 107, 043028 (2023) and velocity-dependent DM models in Phys. Rev. D 108, 083027 (2023).

Emmanuel Moulin is the Research Director at the Irfu/DPhP Institute at CEA, University Paris-Saclay, France. He has worked in gamma-ray astronomy since 2005 with the H.E.S.S. collaboration and the CTA consortium. He has served as a physics convener for fundamental physics/dark matter working groups, a member of the H.E.S.S. observing committee, and on publication boards for H.E.S.S. and CTA. As a CEA expert in astroparticle physics and gamma-ray astronomy, he is deeply involved in Galactic Center observations, including the H.E.S.S. inner Galaxy survey. He is the main author of the discovery paper of the first Galactic Pevatron and is currently searching for TeV emission at the base of the Fermi Bubbles. He has performed dark matter searches in various astrophysical environments, including the inner Galactic halo, dwarf galaxy satellites, Galactic subhalos, Galactic globular clusters, and nearby galaxy clusters. He was the main editor of the CTA dark matter program published in 2018 and has published over 40 papers as a main author, including three in Physics Review Letters and one in Nature.