Overview
- A team led by Yuji Urata published a Nature Astronomy paper on Wednesday that presents JCMT0402-0424, nicknamed Shadow Blaster, as the most plausible source of the high-energy neutrino IC 210922A.
- JCMT0402-0424 is a compact, dusty star-forming galaxy about 11 billion light-years away that appears as four images because a foreground massive elliptical galaxy gravitationally lenses it and places it inside IceCube’s 90% localization.
- The identification relies on coordinated submillimeter and radio imaging from JCMT, SMA and ALMA plus spectroscopic measurements from Gemini that fixed the lens redshift and enabled lens-mass modeling.
- Extensive electromagnetic follow-up in 2021 found no convincing gamma-ray, X-ray, or optical transient tied to IC 210922A, a gap that makes the lensed dusty galaxy a compelling alternative to black-hole sources but leaves the association provisional.
- If confirmed, the paper says compact dusty starbursts like Shadow Blaster could be efficient cosmic-ray calorimeters and might account for up to roughly 20% of IceCube’s diffuse high-energy neutrino background, but independent tests of the lensing, amplification and neutrino production are still needed.