Discovery will shed new light on universe
CITY TEAM HELPS TRACK NEUTRINO
A SINGLE ghost-like sub-atomic particle captured on Earth after a journey of four billion light years could help solve a cosmological conundrum that has vexed scientists for more than 100 years.
The path taken by the high-energy neutrino, the first of its type detected – by an international team including scientists from the University of Leicester – was traced to its likely source, a distant galaxy with a giant black hole at its heart.
Its appearance provides a smoking gun that may help astronomers finally unravel the century-old riddle of highenergy cosmic rays.
The rays, consisting of fast-moving elementary particles, rain down on Earth from space posing a threat to astronauts and even the crews and passengers of commercial jets.
But how they are created and where they come from has been a mystery.
The neutrino discovery, reported in the journal Science, points towards one likely origin, powerful jets of accelerated particles fired from the poles of rapidly rotating supermassive black holes.
The neutrino was detected on September 22 by the IceCube observatory, a mile beneath the South Pole.
There, a grid of more than 5,000 super-sensitive sensors picked up the characteristic blue light emitted as the neutrino interacted with the ice.
Having almost no mass and passing right through planets, stars and anything else in its way, the particle travelled in a straight line from its point of origin to Earth.
As a result, astronomers were able to track its trajectory back across billions of light years to its probable source. The search led to a “blazar”, a class of galaxy containing a supermassive black hole four billion light years away just left of the constellation Orion.
A key feature of blazars is twin jets of light and elementary particles that shoot from the poles of the whirlwind of material surrounding the black hole.
Professor Paul O’Brien, of Leicester, said: “Neutrinos rarely interact with matter. To detect them at all from the cosmos is amazing, but to have a possible source identified is a triumph.
“This result will allow us to study the most distant, powerful energy sources in the universe in a new way.”
Being able to detect high energy neutrinos will provide yet another window on the universe, said the scientists.
Another cosmic “messenger”, gravitational waves, was announced in February 2016.
France Cordova, director of the US National Science Foundation (NSF) that manages the IceCube laboratory, said: “The era of multi-messenger astrophysics is here.
“Each messenger, from electromagnetic radiation, gravitational waves and now neutrinos, gives us a more complete understanding of the universe and important insights into the most powerful objects and events in the sky.”