Combined Search for Neutrinos from Dark Matter Annihilation in the Galactic Centre using ANTARES and IceCube (1908.07300v1)

Abstract: The ANTARES and IceCube neutrino telescopes have both searched for neutrinos from dark matter annihilation in the Galactic Centre, putting limits on the thermally-averaged dark matter self-annihilation cross section $\langle \sigma_A \upsilon \rangle$. For WIMP masses above 100 GeV, the most stringent limits were obtained by the ANTARES neutrino telescope, while for lower masses, limits achieved by IceCube are more competitive. The limits obtained by the two detectors are of comparable order of magnitude for WIMP masses going from 50 to 1000 GeV, making this mass range particularly interesting for a combined analysis. In this contribution, we present the limits of the first combined search for dark matter self-annihilation in the centre of the Milky Way using ANTARES and IceCube. The model parameters and the likelihood method were unified, thereby providing a benchmark for future dark matter searches conducted by each collaboration. By combining data of both detectors, we obtained improved limits with respect to the original limits published by the two collaborations.

• The paper demonstrates a combined analysis that improves sensitivity to neutrino signals from WIMP annihilation across a mass range of 50–1000 GeV.
• It employs binned likelihood techniques and unified frameworks with NFW and Burkert profiles to set upper limits on the dark matter annihilation cross-section.
• The results constrain WIMP model parameters and lay the groundwork for future multi-detector collaborations in dark matter research.

Combined Search for Neutrinos from Dark Matter Annihilation in the Galactic Centre using ANTARES and IceCube

The paper presents a combined analysis of neutrino data collected by two prominent detectors—ANTARES and IceCube—aimed at probing dark matter (DM) annihilation in the Galactic Centre. This combined search is particularly focused on detecting neutrinos as secondary particles that are theorized to result from the self-annihilation of Weakly Interacting Massive Particles (WIMPs), a leading candidate for DM. The self-annihilation cross-section, denoted as $\langle \sigma_A \upsilon \rangle$, is a crucial parameter in this investigation.

Methodology and Results

The research emphasizes unifying the analysis frameworks of ANTARES and IceCube, each of which previously delivered competitive, albeit limited, results over different segments of WIMP mass ranges. For WIMP masses exceeding 100 GeV, ANTARES provided more stringent limits, while IceCube achieved stronger results for lower masses. By leveraging a combined data set ranging from 50 to 1000 GeV, the paper successfully enhanced the sensitivity to the thermally averaged cross-section across this substantial mass window.

The methodology employed involved using binned likelihood techniques to integrate data from both sensors. The likelihood function is constructed by examining the Poisson probability of observed events contingent on the expected signal and background models, accounting for the relative efficiencies of the two telescopes. For signal PDFs, the paper favored the PPPC4 DM annihilation spectra for consistency between both detectors.

Two halo profiles were explored—the Navarro-Frenk-White (NFW) and the Burkert profile—to calculate the astrophysical J-factor, which quantifies the line-of-sight DM density integral over the region of interest. This analysis revealed no significant neutrino signal attributable to DM annihilation, thereby setting upper limits on $\langle \sigma_A \upsilon \rangle$.

Numerical Insights and Observations

The paper delivered separate results for all channels of WIMP annihilation considered: $W^+W^-$, $\tau^+\tau^-$, $\mu^+\mu^-$, and $b\bar{b}$. Whereas results for the NFW profile showed consistent improvements over individual detector efforts, only the Burkert profile in the $b\bar{b}$ channel was dominated by IceCube limits. This suggests that the combined analysis generally enhances detection sensitivity when data sets are unified.

Implications and Future Directions

While the paper successfully illustrates the advantages of combined analyses, it highlights areas for further research optimizations. The joint analysis provides a precedent for future collaborations which could extend to incorporate more extensive data sets or deploy an unbinned likelihood approach for enhanced statistical precision.

At a theoretical level, these limits further constrain the parameter space for WIMP models, informing cosmological simulations and indirect detection strategies. Practically, improved sensitivity in the combined analysis may guide the development of more comprehensive, possibly multi-modal, detection frameworks.

Looking forward, the integration of such neutrino observatories in coordinated DM campaigns could spark enhancements in both experimental setup and analytical technique. This research thereby contributes to a rigorous foundation for future interdisciplinary efforts in tackling the enigma of dark matter.