Laurel Kornfeld
July 15th, 2018
An artist’s concept of the Fermi Gamma-ray Space Telescope.
Credits: NASA
A cosmic neutrino detected by NASA’s Fermi Gamma-ray Space Telescope was found to have originated in a gamma ray emitted by a supermassive black hole 3.7 billion light years away at the center of a galaxy in the constellation Orion.
The discovery, made by an international team of scientists, marks the first time a high-energy neutrino from beyond the Milky Way has been traced to its place of origin as well as the furthest any neutrino has been known to travel.
Neutrinos are high-energy, hard-to-catch particles likely produced in powerful cosmic events, such as supermassive black holes actively devouring matter and galaxy mergers. Because they travel at nearly the speed of light and do not interact with other matter, they are capable of traversing billions of light years.
By studying neutrinos, scientists gain insight into the processes that drive powerful cosmic events, including supernovae and black holes.
Gamma rays are the brightest and most energetic form of light, which is why scientists use them to trace the sources of neutrinos and cosmic rays.
“The most extreme cosmic explosions produce gravitational waves, and the most extreme cosmic accelerators produce high-energy neutrinos and cosmic rays,” explained Regina Caputo of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and analysis coordinator for the Fermi Large Area Telescope Collaboration. “Through Fermi, gamma rays are providing a bridge to each of these new cosmic signals.”
Scientists found this particular neutrino on September 22, 2017, using the National Science Foundation‘s (NSF) IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station. They then traced the neutrino to its origin in a gamma ray blast within the distant supermassive black hole using Fermi.
“Again, Fermi has helped make another giant leap in a growing field we call multimessenger astronomy. Neutrinos and gravitational waves deliver new kinds of information about the most extreme environments in the universe. But to understand what they’re telling us, we need to connect them to the ‘messenger’ astronomers know best–light,” emphasized Paul Hertz, director of NASA’s Astrophysics Division in Washington, DC.
IceCube tracked the neutrino, which hit Antarctica with 300 trillion electron volts. Its extremely high energy level meant it likely came from beyond our solar system. Its galaxy of origin, with which scientists are familiar, is a blazar, a galaxy with an extremely bright and active central supermassive black hole that blasts out jets of particles in opposite directions at nearly the speed of light.
Blazars have several million to several billion times the mass of our Sun. Scientists find them when one of the jets they emit travels in the direction of Earth.
Yasuyuki Tanaka of Japan’s Hiroshima University was the first scientist to link the neutrino to a specific blazar known as TXS 0506+056, which has recently shown increased activity. Fermi keeps track of approximately 2,000 blazars.
Followup observations of TXS 0506 were conducted with the Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) NASA’s Neil Gehrels Swift Observatory, and various other observatories.
Two papers on the discovery have been published here and here in the journal Science.
Video courtesy of NASA Goddard
Laurel Kornfeld
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.
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