Author: Emily Conover / Source: Science News for Students
A zippy little subatomic particle has been traced back to its source. This neutrino was born in a flaring galaxy 4 billion light-years away.
This discovery solved a longstanding cosmic whodunit.Scientists had long puzzled where certain high-energy particles from space were born. These bits of matter can batter Earth at energies that outstrip the world’s most advanced particle accelerators. Now, physicists report finding the source of an energetic neutrino. This cosmic voyager came from a type of distant bright galaxy called a blazar. Owing to a powerful black hole at its core, this type of galaxy flings out particles. They fly across the cosmos blindingly fast — some at nearly the speed of light
Other cosmic sources for high-energy neutrinos also may exist. But on July 12, scientists announced online, in Science, the discovery that blazars create some of those neutrinos.
“This is super exciting news,” says Angela Olinto at the University of Chicago in Illinois. She’s an astrophysicist who was not involved with the new research. The new finding, she says, marks “the beginning of what we call neutrino astronomy.” It uses the lightweight — indeed, nearly massless — neutrinos to unveil secrets of cosmic oddities (such as those blazars).
The new data suggest that blazars also emit cosmic rays. This second type of energetic particle is produced together with neutrinos.
Until now, where high-energy cosmic rays come from has been poorly understood. In fact, until now, “nobody has ever been able to pinpoint a source [of] them,” says Francis Halzen. He’s an astrophysicist at the University of Wisconsin–Madison. He’s also a research leader of IceCube, the Antarctic neutrino observatory that detected the particle.
IceCube is located at the South Pole. It was constructed within a cubic kilometer (a quarter cubic mile) of ice. Thousands of sensors embedded within the ice measure the light produced when neutrinos slam into ice. On September 22, 2017, IceCube detected a neutrino with an energy of nearly 300 trillion electron volts! (For comparison, high energy protons at the Large Hadron Collider in Geneva, Switzerland, reach only some 6.5 trillion electron volts.)
Hunting the neutrino’s birthplace
Physicists…
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