On the sensitivity of CTA to gamma-ray boxes from multi-TeV dark matter

TL;DR

This paper evaluates the Cherenkov Telescope Array's potential to detect distinctive gamma-ray spectral features called gamma-ray boxes from multi-TeV dark matter annihilation, offering a promising avenue for probing otherwise inaccessible dark matter models.

Contribution

It provides a detailed sensitivity analysis for CTA to detect gamma-ray boxes from high-mass dark matter, identifying models that can be tested and highlighting CTA's unique discovery potential.

Findings

CTA can probe gamma-ray boxes up to tens of TeV.

Sensitivity reaches annihilation cross sections of 10^{-27}-10^{-26} cm^3/s.

Identifies particle physics models as benchmarks for future searches.

Abstract

Collider, direct and indirect searches for dark matter have typically little or no sensitivity to weakly interacting massive particles (WIMPs) with masses above a few TeV. This rather unexplored regime can however be probed through the search for distinctive gamma-ray spectral features produced by the annihilation of WIMPs at very high energies. Here we present a dedicated search for gamma-ray boxes -- sharp spectral features that cannot be mimicked by astrophysical sources -- with the upcoming Cherenkov Telescope Array (CTA). Using realistic projections for the instrument performance and detailed background modelling, a profile likelihood analysis is implemented to derive the expected upper limits and sensitivity reach after 100 h of observations towards a $2^\circ\times2^\circ$ region around the Galactic centre. Our results show that CTA will be able to probe gamma-ray boxes down to annihilation cross sections of $10^{-27}-10^{-26}\,\text{cm}^3\text{/s}$ up to tens of TeV. We also identify a number of concrete particle physics models providing thermal dark matter candidates that can be used as target benchmarks in future search campaigns. This constitutes a golden opportunity for CTA to either discover or rule out multi-TeV thermal dark matter in a corner of parameter space where all other experimental efforts are basically insensitive.