Elusive neutrinos are caught in a stream from a black hole hidden in dust

A unique observatory buried in pristine Antarctic ice has detected a stream of elusive neutrino particles emanating from the center of a distant galaxy hidden in dust.

The IceCube observation at the South Pole is only the second detection of a source of cosmic neutrinos, and scientists hope it can shed light on what goes on inside supermassive black holes.

Neutrinos are weird. They are everywhere, but most of the time they don’t interact with other particles or any type of matter. This is because they have very little mass and no electrical charge. For this reason, they are incredibly difficult to detect. But their complete indifference to their surroundings also means that, unlike other particles, they are not distracted from their path, traveling vast distances in straight lines from their sources. This means that once astronomers know how to detect them, they can trace the origin of neutrinos much more easily than other types of particles.

Related: ‘Neutrino factories’ may hold clues to cosmic ray mystery

An international team of scientists reported the discovery of such a stream of neutrinos from a galaxy known as NGC 1086 (sometimes referred to as Messier 77 or the Kalmar Galaxy). NGC 1086 is a dusty galaxy very similar in shape to the Milky Way. However, NGC 1086 produces stellar flares at a much faster rate than our galactic home and orbits a black hole much more massive than the one at the center of the Milky Way.

This hungry black hole, devouring massive amounts of material, forms the core of a blazing active galactic nucleus that emits bright bursts of high-energy cosmic rays and charged particles that outshine the galaxy’s stars. However, much of the black hole’s crackle is hidden from view because the center of the galaxy is hidden by a thick ring as seen from Earth. However, neutrinos, with their ability to pass through matter, leave this ring and reach our planet intact.

“We are peering into the active regions of the galaxy NGC 1068 at a distance of 47 million light years,” said Gary Hill, associate professor of physics at the University of Adelaide in Australia and one of the authors of the paper. (will open in a new tab). “By observing the neutrinos it emits, we can learn more about the extreme particle acceleration and formation processes that take place inside the galaxy, which until now was not possible, since other high-energy emissions cannot escape from it.”

The discovery makes NGC 1068 only the second source of cosmic neutrinos ever identified. In 2018, the IceCube observatory detected a stream of neutrinos emanating from the active galactic nucleus of a galaxy known as TXS 0506+056.

This galaxy, located in the constellation of Orion, is 100 times farther from Earth than NGC 1068, but emits a jet of material at almost the speed of light, aimed directly at Earth. This makes any emission from TXS 0506+056 much easier to detect than NGC 1068.

Hubble image of the spiral galaxy NGC 1068

Galaxy NGC 1068, also known as Messier 77, resembles the Milky Way but has a giant active black hole at its center. (Image credit: NASA/ESA/A. van der Hoeven)

“Following the hype in 2018 caused by the discovery of neutrinos from TXS 0506+056, even more exciting is the discovery of a source producing a steady stream of neutrinos that we can observe with IceCube,” Hill said. “The fact that neutrinos can escape from these dark regions of the universe means they are also difficult to detect.”

The IceCube Observatory is a unique structure. It consists of more than 5,000 detectors submerged 0.9 to 1.5 miles (1.5 to 2.5 kilometers) deep in pristine Antarctic ice. Suspended by 86 vertical cables spaced 125 meters apart, the detectors detect tiny bursts of blue light produced when high-energy neutrinos crash into the atomic nuclei of ice molecules.

The observatory, built in the 2000s, has been operating since 2010. A recent study analyzed high-energy neutrino detections made between 2011 and 2020 looking for possible sources of these particles among known active galaxies. Computer simulations have previously suggested that active black holes, such as those at the center of NGC 1068, should be able to accelerate particles and eject them into intergalactic space along with bursts of high-energy radiation. Scientists expect other similar galaxies to produce their own neutrino showers.

“One neutrino can single out a source. But only a few neutrino observations will reveal the hidden core of the most energetic space objects,” Francis Halzen, professor of physics at the University of Wisconsin-Madison and principal investigator of the IceCube project. , said in a separate statement (will open in a new tab). “IceCube has accumulated about 80 teraelectronvolt energy neutrinos from NGC 1068, which is not yet enough to answer all our questions, but they are definitely the next big step towards realizing neutrino astronomy.”

Astronomers are currently planning to build a second-generation IceCube detector that can detect a thousand times more neutrinos and detect five times fainter sources. Gradually, the hidden universe will open up, leading to a new era in astronomy, according to astronomers.

NGC 1068 could become the “standard candle” for future neutrino research, Theo Glauch, a research fellow at the Technical University of Munich (TUM) in Germany and co-author of the paper, said in a statement. The galaxy, discovered in 1780, is well known to astronomers and has been studied for centuries.

The study (will open in a new tab) published in the journal Science November 4.

Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and on Facebook.

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