Year: 2026
Type: preprint
Abstract: The deep potential wells of galaxy clusters provide some of the strongest constraints on the velocity-dependent ($p$-wave) annihilation of weakly interacting massive particle (WIMP) dark matter. Cross-correlating high-latitude Fermi-LAT 16.3-year data with the western Galactic hemisphere eROSITA map facilitates high-sensitivity tests. A blind composite matched-filter scan of the cross-correlated spectrum for the $χχ\toγγ$, $γZ$, and $γh$ annihilation-line triad of a single WIMP $χ$ finds $m_χc^2\simeq71.9$ and $67.5$ GeV triads, each with a local $Z$-score $\sim3$ and a (henceforth global) $1.6σ$ (trial-corrected by pixel shuffles; $1.8$-$2.1σ$ in Monte Carlo and analytic estimates), insensitive to details of detrending, sky masks, and filters. Scanning for the line nonad of two cross-annihilating WIMPs finds $66.4$ and $71.9$ GeV masses (with a weak $69.2$ GeV cross-annihilation triad) at $2.3σ$. The leading $\sim72$ GeV triad coincides with the mass implied by interpreting the recently reported $\sim43.2$ GeV $γ$-ray line in three nearby clusters as its $γZ$ channel. At this externally fixed mass, the triad reaches $3.0σ$ alone, and $5.1σ$ when combined with the reported line ($3.9σ$ under alternative assumptions). The triad, absent from the ambient (X-ray-uncorrelated) spectrum, presents in different Galactic sectors, strengthens under cosmological (positive) but not negative redshift broadening $Δz$, and peaks at $Δz\simeq 0.05$, consistent with expectations; its two non-$43$ GeV channels reach $2.3σ$ by themselves. Measured (not loss-corrected) intrinsic cross sections are a few $10^{-19}$ cm$^3$ s$^{-1}$ for WIMPs tracing the X-ray gas.
Source: arXiv (Cornell University)
Author: Keshet, Uri
Institution: Ben-Gurion University of the Negev
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Israel Science Foundation
Awards: G2837684338, G518288856
OpenAlex ID: W7164888797