CTA Sensitivity on TeV scale Dark Matter Models with Complementary Limits from Direct Detection

TL;DR

This study evaluates the sensitivity of the Cherenkov Telescope Array (CTA) to TeV scale dark matter models through gamma-ray observations of dwarf galaxies, comparing its potential with future direct detection experiments like XENONnT.

Contribution

It provides the first detailed simulation of CTA's ability to detect or constrain scalar portal dark matter models, specifically inverse seesaw and inert doublet models, using gamma-ray data.

Findings

CTA improves gamma-ray detection limits over previous experiments.

CTA sensitivity is weaker than XENONnT for the inert doublet model.

CTA can potentially detect dark matter signals at the thermal relic cross-section.

Abstract

With ever increasing pressure from collider physics and direct detection experiments, particle physics models of TeV scale dark matter are gaining more attention. In this work, we consider two realizations of the class of scalar portal dark matter scenarios -- the inverse seesaw model and the inert doublet model. Observations by the Cherenkov Telescope Array (CTA) of very-high-energy $\gamma$ rays from dark matter annihilation in the context of these models are simulated for the Draco and Sculptor dwarf spheroidal galaxies, and later analyzed using ctools. We study the potential of CTA for the 5$\sigma$ detection of a dark matter annihilation signal. In the absence of a signal, we also derive the 2$\sigma$ upper limits on the annihilation cross-section. We compare our projected CTA sensitivity against the projected sensitivity of the next generation of direct detection experiment, i.e. XENONnT. Although the limits from CTA are significantly improved compared with the previous generations of $\gamma$-ray experiments, they are still $\sim2$ orders of magnitude above the thermal relic cross-section for the considered targets. In the case of the inverse seesaw model, the constraint from the future direct detection experiment XENONnT is much weaker than the CTA sensitivity, whereas for the inert doublet model, XENONnT gives a bound an order of magnitude stronger compared to the CTA limits.