IceCube Neutrino Observatory traces ghost particle to distant galaxy

PHOTO OF THE DAY: NASA's Fermi Traces Source of Cosmic Neutrino to Monster Black Hole |

Neutrino captured in South Pole might lead the path to new explorations

For the first time, scientists have found the source of a high-energy ghostly particle, known as neutrino, that travelled 3.7 billion years at nearly the speed of light to reach Earth.

The discovery is being announced in a series of papers by an global array of physicists and astronomers in Science and the Astrophysical Journal, and in a news conference sponsored by the National Science Foundation, which funds the IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station.

According to scientists, the discovery of these particles allows them to study the universe in a brand-new way, hinting that this might allow them to track the origin of cosmic rays for the very first time.

Because cosmic rays are charged particles, powerful magnetic fields throughout space distort their trajectories. Some theorized neutrinos and galactic cosmic rays, beams of high-energy radiation, were produced by the same faraway phenomena.

Now, the IceCube Collaboration reports the detection of a high-energy neutrino event whose arrival direction was consistent with a known blazar, a type of quasar in which material falling into a supermassive black hole produces a jet oriented directly along the line of sight to Earth. Researchers there quickly sent out alerts to ground- and space-based telescopes in hopes of finding the neutrino's cosmic source. Together, they settled on a supermassive black hole in the center of a galaxy 3.7 billion light years away.

This is a type of active galaxy called a blazar, with a supermassive black hole with millions to billions of times the Sun's mass that blasts jets of particles outward in opposite directions at almost the speed of light. This blazar, designated TXS 0506+056, is about four billion light years from Earth. That's what the IceCube neutrino detector in Antarctica watches for, and in September 2017, that's what it saw.

Through the IceCube particle detector, Naoko Kurahashi Neilson, PhD, an assistant professor in Drexel's College of Arts and Sciences, and her team were able to show that neutrinos originate from blazars. In a decade of Fermi observations of this source, this was the strongest flare in gamma rays, the highest-energy photons. This independent observation greatly strengthens the initial detection of a single high-energy neutrino and adds to a growing body of data that indicates TXS 0506+056 is likely the first identified accelerator of the highest energy neutrinos and cosmic rays, Whitehorn said.

IceCube, an global observatory run by 300 scientists from 12 countries, consists of more than 5,000 sensitive photomultiplier tubes embedded in grid encompassing 1 cubic kilometer of ice at the South Pole. Other instruments operating at optical, radio and X-ray wavelengths also made detections.

This discovery marks a new era of neutrino astronomy. But so much about the ghostly particles, including where they come from, remains unknown. This will clearly help the scientists examine objects in deep space. Where does the rain of high-energy particles from space known as cosmic rays come from?

But these ultra-high-energy cosmic rays are also the only plausible source of the high-energy neutrinos, which fly true, even across intergalactic distances.

"In our case, we saw an active galaxy, which is a large galaxy containing a huge black hole at its centre", explains Kowalski. Just two individual sources of astrophysical neutrinos were previously known (the Sun and a nearby supernova), with no new sources discovered for 30 years.

The lure of neutrinos for astronomy is that it is possible to trace them back to their origins.

NSF's IceCube observatory is operated by an global collaboration that includes more than 300 scientists from 49 different institutions in 12 countries. For the IceCube detector, an worldwide consortium of scientists headed by the University of Wisconsin in Madison (USA) drilled 86 holes into the Antarctic ice, each 2500 metres deep. "For years, we've had a long list of potential sources for high-energy neutrinos". Its 3D grid of sensors embedded in the ice detected the neutrino when it smashed into the nucleus of a water molecule.

Hard to detect, neutrinos are extremely tiny particles and are among the most abundant in the universe.

Latest News