Dark matter and fundamental physics with the Cherenkov Telescope Array

Abstract

The Cherenkov Telescope Array (CTA) is a project for a next-generation observatory for very high energy (GeV–TeV) ground-based gamma-ray astronomy, currently in its design phase, and foreseen to be operative a few years from now. Several tens of telescopes of 2–3 different sizes, distributed over a large area, will allow for a sensitivity about a factor 10 better than current instruments such as H.E.S.S, MAGIC and VERITAS, an energy coverage from a few tens of GeV to several tens of TeV, and a field of view of up to 10°. In the following study, we investigate the prospects for CTA to study several science questions that can profoundly influence our current knowledge of fundamental physics. Based on conservative assumptions for the performance of the different CTA telescope configurations currently under discussion, we employ a Monte Carlo based approach to evaluate the prospects for detection and characterisation of new physics with the array. First, we discuss CTA prospects for cold dark matter searches, following different observational strategies: in dwarf satellite galaxies of the Milky Way, which are virtually void of astrophysical background and have a relatively well known dark matter density; in the region close to the Galactic Centre, where the dark matter density is expected to be large while the astrophysical background due to the Galactic Centre can be excluded; and in clusters of galaxies, where the intrinsic flux may be boosted significantly by the large number of halo substructures. The possible search for spatial signatures, facilitated by the larger field of view of CTA, is also discussed. Next we consider searches for axion-like particles which, besides being possible candidates for dark matter may also explain the unexpectedly low absorption by extragalactic background light of gamma-rays from very distant blazars. We establish the axion mass range CTA could probe through observation of long-lasting flares in distant sources. Simulated light-curves of flaring sources are also used to determine the sensitivity to violations of Lorentz invariance by detection of the possible delay between the arrival times of photons at different energies. Finally, we mention searches for other exotic physics with CTA

Measurement of beauty and charm production in deep inelastic scattering at HERA and measurement of the beauty-quark mass

“…In the near future, Cta should be able to significantly improve on line searches for the GC region [82,83], by probing annihilation cross sections smaller than 10 −26 cm 3 /s on most of the mass range. 8 Concerning antiprotons, some improvement should come from upcoming Ams-02 data [85].…”

Multi-frequency search for Dark Matter: the role of HESS, CTA, and SKA

“…However, both HESS and the upcoming Cherenkov Telescope Array (CTA) [13,4] are admirably suited to probe large mass WIMPs. In this regard we aim to examine how far into the high-mass parameter space these projects can explore, in a manner similar to earlier works on the topic [14,15]. This being of particular significance as Fermi-LAT is less effective in constraining high-mass WIMPs, particularly those annihilating via τ lepton states (or other channels that provide harder γ-ray spectra).…”

Can a millicharged dark matter particle emit an observable γ-ray line?

“…Similarly this would have given a huge amount of cosmic rays. 4 Therefore, due to several reasons, a line observed at the present sensitivities with energies above the Z mass could not be attributed at all to a millicharged DM decaying in neutrino and photon through one of the operators under study.…”

“…The forthcoming Cherenkov telescopes [4], the current Fermi large area telescope [5] and the HESS instrument [6] will allow to probe this possibility with further sensitivity. If such a signal is observed in the near future, the question of the identification of the DM particle that could have caused it will become crucial.…”