Fermi-eROSITA cross-correlations suggest annihilation lines of ∼70 GeV WIMPs
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→γγ, γZ, and γh annihilation-line triad of a single WIMP χ finds mχc2≃71.9 and $67.5$ GeV triads, each with a local Z-score ∼3 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 ∼72 GeV triad coincides with the mass implied by interpreting the recently reported ∼43.2 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≃ 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 cm3 s−1 for WIMPs tracing the X-ray gas.
Related
- The XMM Cluster Survey: Cross-Calibration of eROSITA and XMM using Dark Energy Survey Y3 Galaxy Clusters
- The XMM Cluster Survey: Cross-Calibration of eROSITA and XMM using Dark Energy Survey Y3 Galaxy Clusters
- FALCON (FERMI-ALMA Calibrator ObservatioN): Cross-matching ALMA Calibrators with Fermi-LAT Blazars
- Detection Forecasting for Blazars at MeV Energies with Fermi-LAT Swift-BAT Cross Match
- Unveiling the Dark Ages: A New Pathway Using Tomographical 21 cm Cosmic Microwave Background Cross-correlations
BibTeX
@misc{keshet2026fermierosita,
title = {{Fermi-eROSITA cross-correlations suggest annihilation lines of $\sim70$ GeV WIMPs}},
author = {Uri Keshet},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.17044},
eprint = {2606.17044},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.17044},
}
RIS
TY - UNPB
TI - Fermi-eROSITA cross-correlations suggest annihilation lines of ∼70 GeV WIMPs
AU - Uri Keshet
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2606.17044
UR - https://arxiv.org/abs/2606.17044
AB - 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→γγ, γZ, and γh annihilation-line triad of a single WIMP χ finds m_χc^2≃71.9 and $67.5$ GeV triads, each with a local Z-score ∼3 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 ∼72 GeV triad coincides with the mass implied by interpreting the recently reported ∼43.2 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≃ 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.
ER -