Probing Dark Matter annihilation in the Galactic Centre with TRIDENT

TL;DR

The work evaluates TRIDENT's future sensitivity to dark matter annihilation in the Galactic Centre using full detector design and all-flavour neutrino detection. It demonstrates that cascade events substantially enhance sensitivity, potentially reaching $\langle \sigma v \rangle \approx 5\times10^{-27}\,{\rm cm^3\,s^{-1}}$ at $m_\chi=10\,{\rm TeV}$, below the thermal relic target. A novel Galactic plane neutrino background from cosmic-ray interactions is incorporated, degrading high-energy sensitivity by up to a factor of ~2 and illustrating possible mimicry of a DM signal. The results are mapped to a concrete $U(1)_{L_i-L_j}$ particle model, showing TRIDENT can probe previously untested regions and provide complementary constraints to gamma-ray and direct-detection experiments.

Abstract

We determine the future sensitivity of the TRIDENT neutrino telescope to dark matter annihilation in the Galactic Centre. By applying the full detector design we show that TRIDENT will probe annihilation rates down to $\langleσv\rangle\approx5\times10^{-27}\,{\rm cm}^3\,{\rm s}^{-1}$ for a $10\,{\rm TeV}$ dark matter, which is below the thermal freeze-out benchmark. The analysis is carried out with all-flavour neutrino interactions, where we demonstrate that cascade events, primarily due to $ν_{e,τ}$, show greater sensitivity to a dark matter signal compared to the more commonly studied track events. Furthermore, we highlight the impact of a previously overlooked background, Galactic neutrinos produced from interactions between hadronic cosmic rays and interstellar gas. We find dark matter sensitivities are more strongly degraded in the high energy region above $\sim 10\, {\rm TeV}$, with a maximal weakening of approximately a factor of $\sim 2$. This effect remains smaller than the uncertainty associated with the dark matter density profile but can nonetheless mimic a positive annihilation signal. We contextualize these results with a concrete particle model and show that TRIDENT will be able to probe the most interesting untested parts of parameter space.

Figures (8)

• Figure 1: Visualisation of the two types of neutrino interactions from the TRIDENTSim framework MortonBlake:2025allflavour, showing an example $\nu_\mu$-CC track event (top) and $\nu_e$-CC cascade event (bottom). The colour of the spheres indicates the photon detection time, with red corresponding to early arrivals and blue to later arrivals, while the radii represent the number of photons detected by each hDOM.
• Figure 2: Expected reconstructed energy spectra in TRIDENT from DM annihilation channels $\chi\chi \rightarrow \tau^+\tau^-$ (top) and $\chi\chi \rightarrow \nu\bar{\nu}$ (bottom) for a DM mass of $m_\chi=100\,\mathrm{TeV}$. The left and right panels correspond to track events with opening angle $\psi < 5^\circ$ and cascade events with $\psi < 20^\circ$, respectively. The annihilation cross-section $\langle\sigma v\rangle$ is adopted from the current KM3NeT limits km3net2025firstdm. The smeared distributions account for the detector’s energy reconstruction uncertainty.
• Figure 3: Reconstructed sky maps of expected DM signals in TRIDENT in Galactic coordinates, extending $\pm40^\circ$ in both latitude and longitude. The signals arise from DM annihilation channels $\chi\chi \rightarrow \tau^+\tau^-$ and $\chi\chi \rightarrow \nu\bar{\nu}$ for a DM mass of $m_\chi = 100,\mathrm{TeV}$. The annihilation cross-section $\langle\sigma v\rangle$ is taken from the current KM3NeT limits km3net2025firstdm. The distributions account for the detector’s angular resolution.
• Figure 4: 95% CL upper limits of TRIDENT on the thermally averaged DM annihilation cross-section $\langle \sigma v\rangle$, as a function of the DM mass for four annihilation channels. The left (right) panel represents the sensitivity obtained from track (cascade) events.
• Figure 5: The event rate of Galactic plane neutrinos background from one randomly generated sky map, together with the DM signal from $\chi\chi\rightarrow \nu\bar{\nu}$ channel and the combined atmospheric and diffuse astrophysical background, for both track (left) and cascade (right) events.