Free Astronomy Magazine September-October 2026

30 SEPTEMBER-OCTOBER 2026 ASTRO PUBLISHING L eft: the field around the gravitationally lensed galaxy nicknamed “Shadow Blaster.” This galaxy lies 11 billion light-years away and sits just behind the bright red galaxy at the center of this image. Center: a close-up of the gravitational lens in which the red foreground galaxy is causing the light from the more distant Shadow Blaster galaxy to bend around it, creat- ing multiple distorted images of the galaxy that appear as yellow arcs. Right: a close-up of the gravitationally lensed Shadow Blaster galaxy. These images were captured with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Gemini North telescope, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation and operated by NSF NOIRLab. [International Gemini Observatory/NOIRLab/NSF/AURA/ALMA (ESO/NAOJ/NRAO). Image Processing: T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), D. de Martin & M. Zamani (NSF NOIRLab). Acknowledgment: PI: Yuji Urata (MITOS Science Co., LTD.)] fication from lensing let ALMA re- solve spatial scales that would other- wise have been extremely difficult to study at this distance. ALMA de- tected several emission lines from carbon monoxide and neutral atomic carbon, establishing a precise red- shift of 2.988 — meaning the light began its journey when the Universe was only a few billion years old, dur- ing the era known as “Cosmic Noon,” when galaxies formed stars at the highest rates in cosmic history. These molecular-line measurements let the astronomers examine the ex- citation and motion of the gas inside the galaxy. The data show no clear sign that a powerful active galactic nucleus dominates its energy output; instead, the gas properties point to an intense, compact episode of star formation. After correcting for grav- itational magnification, the team es- timates the galaxy is forming hun- dreds of solar masses of stars per year, with large quantities of gas and dust packed into a compact central region. That density matters for the neutrino question: it creates condi- tions where energetic cosmic rays can repeatedly collide with sur- rounding matter, producing short- lived particles that decay into gamma rays and neutrinos. Dense, dusty starbursts may act as cosmic- ray “calorimeters” — trapping ener- getic particles long enough for much of their energy to be converted into these secondary particles. The expected neutrino output of any single dusty star-forming galaxy is modest, and the study does not claim Shadow Blaster has been con- clusively identified as the source of IC 210922A. But the galaxy’s loca- tion, rarity, compact structure, and gas-rich core together strengthen the case for a possible association — and suggest that similar galaxies could contribute collectively to the diffuse background of high-energy neutrinos observed across the sky. Population modeling in the study in- dicates that compact-core dusty star- burst galaxies could account for roughly 15%, and at most around 20% in the models considered, of the diffuse astrophysical neutrino flux between tens of teraelectron- volts and petaelectronvolt energies. That would be a meaningful but subdominant contribution — imply- ing that several different classes of astronomical objects are likely re- sponsible for the neutrinos IceCube and other observatories detect. The result is a clear demonstration of multi-messenger astronomy at work: combining a particle signal with ob- servations across the electromag- netic spectrum. It also underscores ALMA’s unique ability to reveal the dense gas, dust, and compact struc- tures hidden inside galaxies that vis- ible light alone cannot penetrate. !