NASA’s Voyager-1 spacecraft is sending back cosmic ray data that has allowed researchers to better understand the cosmos’ exotic dark matter, reports Bruce Dorminey for Forbes Magazine. What they found was that analysis of the spacecraft’s cosmic ray detections beyond the heliopause (where the solar wind’s influence ends and the flux of low energy galactic cosmic rays begins), provided no evidence of dark matter. The researchers theorized that if dark matter was present, they would have found a higher density of lower energy cosmic rays in the data.
Caltech physicist Alan Cummings, who is part of the Voyager science team, explains that Voyager’s cosmic ray detector was designed specifically to look for galactic cosmic rays—low-energy cosmic rays that can only be detected outside our solar system. While most scientists believe cosmic rays originate within supernova remnants, some are thought to be related to dark matter. These rays—charged elemental particles that sometimes move at velocities approaching that of light—are helping researchers understand dark matter’s lower mass limits. The idea is that at least some dark matter particles present in the galaxy will annihilate into particle-antiparticle pairs, Dorminey writes—however, this is rare.
Scientists have proposed that dark matter could be made of microscopic black holes. A microscopic black hole would be no bigger than a nucleus of the element Xenon, explains Pierre Salati, a physicist at France’s Laboratoire d’Annecy-le-Vieux de Physique théorique. Researchers hoped that analyzing the new Voyager data to look for the evaporation of black holes emitting cosmic rays would be observable. But it wasn’t, leading Salati to conclude that these cosmic rays may not exist. “The idea is that the black holes evaporate and that evaporation emits cosmic rays,” he said. Despite the lack of evidence, researchers still plan to analyze data sent back from Voyager as long as possible.