Preprint Claims ~100 TeV Neutrinos From Milky Way’s Fermi Bubbles; Confirmation Pending

A new arXiv preprint claims to have found a statistically significant signal of roughly 100 tera-electron-volt neutrinos from the Milky Way’s Fermi bubbles using public IceCube data, a result that could matter for high-energy astrophysics if it holds up. But the claim is preliminary: The paper is not peer-reviewed, and as of June 23 there was no public statement from the IceCube Collaboration validating it and no public independent confirmation from other neutrino observatories such as KM3NeT or Baikal-GVD.

If borne out, the result would be a notable multimessenger finding, linking neutrinos, gamma rays and X-rays to the giant outflows above and below the center of the Milky Way. More importantly, it would strengthen the case that at least part of the bubbles’ emission has a hadronic origin, meaning high-energy protons or heavier nuclei are being accelerated and then colliding with matter, rather than the signal coming entirely from high-energy electrons.

The paper, “Fermi bubbles detected in ∼100 TeV neutrinos,” was posted to arXiv as arXiv:2606.22387v1. The arXiv record shows it was submitted June 21. Its authors are Uri Keshet of Ben-Gurion University of the Negev and Ilya Gurwich of Qedma Quantum Computing.

Keshet and Gurwich analyzed IceCube’s public 12-year HESE, or high-energy starting events, dataset, which contains 164 events. They compared the neutrino sky map with gamma-ray maps from NASA’s Fermi Large Area Telescope and X-ray maps from eROSITA, the German-led X-ray telescope that has revealed large shell-like structures around the bubbles.

The preprint reports a correlation of more than 3 sigma between IceCube events and the Fermi-LAT sky map outside the crowded Galactic plane. It further says the analysis finds both Fermi bubbles at high latitudes, above 30 degrees north and south of the plane, at more than 4 sigma significance when using bubble shells localized with eROSITA data. “We detect (>4σ) both bubbles at high (|b|>30◦) latitudes, with a local excess (>5σ) mainly in their X-ray bright eastern shells,” the authors wrote in the abstract.

The authors interpret the putative signal as evidence that shocks in the bubbles are accelerating ions to energies above a peta-electron-volt, or PeV. They estimate about 10^54.5 ergs of relativistic-ion energy in each bubble, with roughly a factor-of-three uncertainty, and an ion-acceleration efficiency of about 10%. The paper also reports what it calls preliminary evidence for neutrinos from the larger eROSITA bubble shells surrounding the Fermi bubbles.

The significance estimates come from empirical null tests in which the photon and X-ray templates are rotated relative to the neutrino sky map. That kind of template-based analysis is likely to face scrutiny over issues such as trial factors, masking choices, exposure weighting and how sensitive the result is to the chosen templates.

The Fermi bubbles were first reported in 2010 in Fermi-LAT data. They are enormous gamma-ray structures extending roughly 10 kiloparsecs above and below the Galactic disk and are widely seen as signs of a past energetic outflow from the Milky Way’s center. A neutrino signal from them was explicitly predicted in a 2012 Physical Review Letters paper. Earlier searches using less IceCube data did not find a significant signal, and a 2017 IceCube/HAWC study constrained some hard hadronic models.

That history is part of what makes the new claim potentially important and why it will need careful checking. For now, it is an independent analysis of public IceCube data, not an IceCube announcement. Before the result can be treated as established, it will need confirmation from the IceCube Collaboration itself or from other neutrino experiments.