beecee Posted July 12, 2018 Posted July 12, 2018 https://phys.org/news/2018-07-century-old-riddle-resolveda-blazar-source.html More than century-old riddle resolved—a blazar is a source of high-energy neutrinos An international team of scientists has found the first evidence of a source of high-energy cosmic neutrinos, ghostly subatomic particles that can travel unhindered for billions of light years from the most extreme environments in the universe to Earth. The observations, made by the IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station and confirmed by telescopes around the globe and in Earth's orbit, help resolve a more than a century-old riddle about what sends subatomic particles such as neutrinos and cosmic rays speeding through the universe. Since they were first detected over one hundred years ago, cosmic rays—highly energetic particles that continuously rain down on Earth from space—have posed an enduring mystery: What creates and launches these particles across such vast distances? Where do they come from? Read more at: https://phys.org/news/2018-07-century-old-riddle-resolveda-blazar-source.html#jCp <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the paper: http://science.sciencemag.org/content/361/6398/147 Neutrino emission from the direction of the blazar TXS 0506+056 prior to the IceCube-170922A alert: Neutrino emission from a flaring blazar Neutrinos interact only very weakly with matter, but giant detectors have succeeded in detecting small numbers of astrophysical neutrinos. Aside from a diffuse background, only two individual sources have been identified: the Sun and a nearby supernova in 1987. A multiteam collaboration detected a high-energy neutrino event whose arrival direction was consistent with a known blazar—a type of quasar with a relativistic jet oriented directly along our line of sight. The blazar, TXS 0506+056, was found to be undergoing a gamma-ray flare, prompting an extensive multiwavelength campaign. Motivated by this discovery, the IceCube collaboration examined lower-energy neutrinos detected over the previous several years, finding an excess emission at the location of the blazar. Thus, blazars are a source of astrophysical neutrinos. Abstract A high-energy neutrino event detected by IceCube on 22 September 2017 was coincident in direction and time with a gamma-ray flare from the blazar TXS 0506+056. Prompted by this association, we investigated 9.5 years of IceCube neutrino observations to search for excess emission at the position of the blazar. We found an excess of high-energy neutrino events, with respect to atmospheric backgrounds, at that position between September 2014 and March 2015. Allowing for time-variable flux, this constitutes 3.5σ evidence for neutrino emission from the direction of TXS 0506+056, independent of and prior to the 2017 flaring episode. This suggests that blazars are identifiable sources of the high-energy astrophysical neutrino flux.
T. McGrath Posted July 14, 2018 Posted July 14, 2018 What is wrong with these people? Are they stuck in the 1960s? Blazars and quasars are what the ignorant call Active Galactic Nuclei. Blazar and quasar were merely placeholders for something we had no idea how to describe at the time. There was only a brief period (between 1963 and 1969) when we had no idea what these objects were. By the 1970s they knew the source were active galaxies, and thus began calling them Active Galactic Nuclei. Then we have the above paper, which is a throw back to 50 years ago.
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