Using ALMA and the Gemini North telescope, an international team linked a high-energy neutrino detected by IceCube to a dust-shrouded starburst galaxy 11 billion light-years away - pointing to a previously overlooked class of cosmic particle accelerator.
A high-energy cosmic neutrino detected in 2021 has been traced to a distant, heavily obscured galaxy nicknamed “Shadow Blaster” - and the source of that particle appears to be not a supermassive black hole, as standard models would predict, but an extraordinarily compact region of intense star formation. The findings, published June 17, 2026 in Nature Astronomy, open a new chapter in multi-messenger astronomy and suggest that a previously overlooked class of galaxy may be responsible for a significant share of the high-energy neutrino flux reaching Earth from across the universe.
Neutrinos are among the most elusive particles in nature. They carry no electric charge, interact only weakly with matter, and travel undisturbed across cosmic distances, making them useful tracers of extreme astrophysical environments. The IceCube Neutrino Observatory, a cubic-kilometre grid of sensors embedded in the Antarctic ice sheet at the South Pole, registered the event designated IC 210922A in September 2021. Its high energy pointed to an origin in one of the universe’s most energetic environments - but the precise source was unknown.
Standard astrophysical models point toward active galactic nuclei as the dominant source of high-energy astrophysical neutrinos: galaxies where supermassive black holes are actively accreting material and generating relativistic jets. When lead author Yuji Urata of Taiwan’s National Central University and colleagues targeted the IceCube coordinates with ALMA - the Atacama Large Millimeter/submillimeter Array - what they found challenged that expectation.
The galaxy in the direction of IC 210922A is formally designated JCMT0402-0424. The team nicknamed it Shadow Blaster: it is virtually invisible in optical light, obscured by dense dust, yet blazes brightly at submillimeter wavelengths where dust emission peaks. According to the NAOJ press release accompanying the study, the galaxy lies approximately 11 billion light-years from Earth, placing it at “cosmic noon” - the era of peak star formation and galaxy assembly, roughly 2 to 3 billion years after the Big Bang.
ALMA observations revealed that Shadow Blaster sits behind a gravitational lens - a massive foreground object whose gravity bends and magnifies the light from the distant galaxy, allowing the team to resolve structure that would otherwise remain undetectable. Inside that magnified image, ALMA detected a compact core measuring roughly 1,500 light-years across, densely packed with gas and dust and forming new stars at an intense rate. No clear signatures of an active supermassive black hole were identified.
Gemini North observations in optical wavelengths confirmed the galaxy’s faintness in visible light, consistent with the heavy dust obscuration seen in submillimeter data.
Researchers propose that Shadow Blaster’s compact starburst core can itself function as a natural particle accelerator, without a black hole. In the theoretical model described in the paper, cosmic rays - high-energy charged particles - are accelerated by the turbulent, dense gas environment of the extreme star-forming region. Those cosmic rays then collide repeatedly with surrounding gas molecules, producing high-energy neutrinos as a by-product of a process known as hadronic interaction.
According to the team’s analysis, compact dusty starburst galaxies at cosmic noon may collectively account for approximately 20% of the diffuse astrophysical neutrino background that IceCube has measured but not yet fully explained. “If confirmed, Shadow Blaster would be the first-ever individual dusty star-forming galaxy directly linked to a high-energy neutrino event,” Space.com reported.
The multi-instrument approach was highlighted by Martin Still, program director at the U.S. National Science Foundation: “This breakthrough shows how particle detectors and telescopes become far more impactful when they work together, opening a powerful multi-messenger window.”
The case is compelling, not conclusive. The positional coincidence between IC 210922A and Shadow Blaster is statistically significant, and the multi-wavelength characterisation by ALMA and Gemini strengthens the association. However, neutrino localisation by IceCube carries inherent angular uncertainty, and a chance alignment cannot be fully excluded based on a single event. The proposed starburst neutrino-production mechanism is physically motivated and passed peer review at Nature Astronomy, but the claim that this galaxy class contributes ~20% of the diffuse background requires confirmation across multiple independent neutrino-galaxy associations.
What the study does establish is a clear demonstration of multi-messenger astronomy’s reach: Shadow Blaster was essentially invisible to conventional optical sky surveys. ALMA found it because it looked at the right wavelengths, in the right direction, prompted by a particle detector buried in ice at the bottom of the world.
The team’s paper, “Compact dusty starbursts at cosmic noon linked to high-energy neutrinos,” is published in Nature Astronomy (DOI: 10.1038/s41550-026-02884-9). Further IceCube events and follow-up campaigns targeting similar dusty starburst galaxies will be needed to determine whether Shadow Blaster is a singular coincidence or the first confirmed member of a new neutrino-source class.
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