For the first time ever, scientists using NASA's
Fermi Gamma-ray Space Telescope have found the source of a high-energy neutrino
from outside our galaxy. The neutrino came from the
eruption of a supermassive black hole at the center of a type of galaxy called
a blazar. The eruption jetted out particles moving near the speed of light.
Collisions inside the jet produced
gamma rays, the highest-energy form of light, and neutrinos,
ghostly particles that rarely interact with matter.
3.7 billion years later, they reached Earth.
On September 22, 2017, a single
high-energy neutrino struck an atom in a water molecule in the Antarctic ice.
The crash produced a particle called a muon.
It raced through the ice so fast it emitted a faint blue glow.
When the muon reached the South Pole, it was tracked by the
IceCube Neutrino Observatory. IceCube scientists found
the original neutrino likely came from beyond our solar system.
They alerted astronomers to be on the lookout for cosmic outbursts possibly
associated with it. NASA's Fermi Gamma-ray Space
Telescope found the source, a blazar it had been watching for some time.
When the neutrino arrived, Fermi saw the blazar
was brighter than it had been over the previous decade.
It's the first time a neutrino could be traced back to a black hole, or to any
source beyond our immediate galactic neighborhood. And it's an important
step forward for a growing field scientists call multimessenger astronomy,
which combines light with new signals like gravitational waves
and neutrinos, to provide new insights on the most
extreme cosmic phenomena.
[Music fades] NASA Astrophysics
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Goddard Space Flight Center www.nasa.gov/goddard