Search for GeV-scale Dark Matter from the Galactic Center with IceCube-DeepCore

TL;DR

This study interrogates GeV-scale dark matter using neutrinos from the Galactic Center with ~9 years of IceCube-DeepCore data, focusing on DM masses from $15~\mathrm{GeV}$ to $8~\mathrm{TeV}$ and annihilation/decay channels that produce neutrinos, including a neutrino-line scenario. A two-dimensional likelihood in reconstructed energy and GC opening angle, together with a data-driven background model via RA scrambling, yields no significant excess; the best-fit point ($m_ ext{DM}=201.6\ \mathrm{GeV}$, $b\bar{b}$, NFW) has a local significance of $2.47\sigma$ but a post-trial significance of $1.08\sigma$. Consequently, the analysis sets stringent 90% CL limits on the thermally averaged annihilation cross-section, $\langle\sigma v\rangle$, at the level of $\sim10^{-24}\ \mathrm{cm^3\,s^{-1}}$ and lower limits on the decay lifetime up to $\tau\sim10^{26}\ \mathrm{s}$ for $m_ ext{DM}$ from $5$ GeV to $8$ TeV, with neutrino-line channels providing the strongest constraints. These results improve IceCube limits over previous work, establish world-leading bounds in several GeV-scale scenarios, and demonstrate the impact of improved low-energy reconstruction and halo-profile considerations for indirect DM searches. The paper also notes that upcoming IceCube-Upgrade will further enhance sensitivity in the GeV regime.

Abstract

Models describing dark matter as a novel particle often predict that its annihilation or decay into Standard Model particles could produce a detectable neutrino flux in regions of high dark matter density, such as the Galactic Center. In this work, we search for these neutrinos using $\sim$9 years of IceCube-DeepCore data with an event selection optimized for energies between 15 GeV to 200 GeV. We considered several annihilation and decay channels and dark matter masses ranging from 15 GeV up to 8 TeV. No significant deviation from the background expectation from atmospheric neutrinos and muons was found. The most significant result was found for a dark matter mass of 201.6 GeV annihilating into a pair of $b\bar{b}$ quarks assuming the Navarro-Frenk-White halo profile with a post-trial significance of $1.08 \;σ$. We present upper limits on the thermally-averaged annihilation cross-section of the order of $10^{-24} \mathrm{cm}^3 \mathrm{s}^{-1}$, as well as lower limits on the dark matter decay lifetime up to $10^{26} \mathrm{s}$ for dark matter masses between 5 GeV up to 8 TeV. These results strengthen the current IceCube limits on dark matter masses above 20 GeV and provide an order of magnitude improvement at lower masses. In addition, they represent the strongest constraints from any neutrino telescope on GeV-scale dark matter and are among the world-leading limits for several dark matter scenarios.

Figures (10)

• Figure 1: Angular resolution of each neutrino flavor in terms of the opening angle from the Galactic Center as a function of neutrino energy.
• Figure 2: Predicted event rate as the function of true neutrino energy for different dark matter masses and channels, assuming Navarro-Frenk-White (NFW) profile and annihilation with $\langle \sigma v \rangle = 10^{-26} (\mathrm{cm^3 \mathrm{s}^{-1}})$.
• Figure 3: Two-dimensional PDFs as a function of reconstructed energy ($E_{reco}$) and reconstructed opening angle relative to the Galactic Center ($\psi_{reco}$) for a DM signal with mass 1000 GeV annihilating into $b\overline{b}$(left) and with mass 100 GeV annihilating into $\nu_\mu \overline{\nu}_{\mu}$(right), both assuming NFW profile.
• Figure 4: Two-dimensional PDF of background estimated as RA-scrambled data.
• Figure 5: Pull distribution between null hypothesis and best-fit signal (left) and the bin-wise test statistic distribution at best-fit signal (right), both shown as a function of reconstructed opening angle and reconstructed energy.