Jacinta Bowler
Jacinta Bowler is a science journalist at Cosmos.
They were published in the Best Australian Science Writing 2023.
Scientists believe they’ve detected multiple neutrinos – also known as ghost particles – in a detector deep below the surface of Antarctica, and they hope it might help unlock hidden secrets deep inside galaxies.
NGC 1068, also known as Messier 77 or the ‘squid galaxy’, is a dusty, spiral galaxy, with gorgeous long arms and gas obscuring its core.
That gas was hiding a secret, which an international team of researchers unlocked using the “IceCube Neutrino Observatory”, discovering the ‘radio quiet’ galaxy in the act of emitting high energy neutrinos.
It would be the first time this has been discovered in a galaxy, according to a paper published in Science.
“We are peering inside active regions of the NGC 1068 galaxy 47 million light years away,” says University of Adelaide physicist Associate Professor Gary Hill. He is a member of the IceCube Collaboration which built and operates the detector at the South Pole.
“We will be able to learn more about the extreme particle acceleration and production processes occurring inside the galaxy, which hasn’t been possible up to now as other high energy emissions can’t escape from it.”
Read more: W boson spotted in Antarctica
Neutrinos are tricky particles to catch. They are high energy but have no electrical charge and almost no mass. They can travel at nearly the speed of light, and blip through whole planets without interacting with them. But the saving grace is that there are a lot of them – scientists suggest that there are trillions of neutrinos passing through our bodies every second.
One way to catch them is through large telescopes like the IceCube Neutrino Observatory – which is 2.5 km under the ice and can detect when neutrinos occasionally create charged particles.
The researchers looked through the IceCube data from 2011 to 2020, using new statistical analysis. They noted 110 known locations in the sky which were gamma ray sources (like blazars and quasars), as these could also be sources of neutrinos.
One of the gamma ray sources was NGC 1068, an active galaxy in the constellation Cetus, around 47 million light years away from us. It’s a well-studied galaxy, and you might have recognised the Hubble Telescope picture of it’s gorgeous hues.
It was only in February this year that thermal imaging uncovered the supermassive black hole inside NGC 1068.
The results, the scientists say, were very exciting. Researchers found more than 79 neutrino events with a significance of 4.2-sigma coming from NGC 1068. This means the likelihood of it being something else is just 0.3%.
Hubble Space Telescope image of Messier 77 spiral galaxy. Credit: NASA, ESA & A. van der Hoeven.
“More data is needed to firmly establish NGC 1068 and other active galactic nuclei as neutrino sources,” Pennsylvania State University physicist Associate Professor Kohta Murase writes in an accompanying piece in Science.
This isn’t the first time scientists have been pretty sure the IceCube Observatory has found neutrinos. In 2018 the team reported that a blazar called TXS 0506+56, was likely emitting neutrinos. Blazars are supermassive black holes with high energy jets blazing out both ends. NGC 1068 doesn’t have these jets and is known as ‘radio-quiet’, but is still able to produce neutrinos.
“This neutrino detection from the core of NGC 1068 will improve our understanding of the environments around supermassive black holes,” says Michigan State University physicist Dr Hans Niederhausen.