Hubble image of the spiral galaxy NGC 1068. Credit: NASA/ESA/A. van der Hoeven
For the first time, evidence of the emission of high-energy neutrinos from the studied galaxy NGC 1068, also known as Messier 77, has been found, allowing its depths to be examined.
This galaxy, which was first observed in 1780, is located 47 million light-years from us and can be seen with large binoculars. The results of the study have been presented in a scientific online seminar with experts, journalists and scientists from around the world and are published in the journal ‘Science’.
The detection was made at the IceCube Neutrino Observatory, supported by the US National Science Foundation (NSF), a huge neutrino telescope covering a billion tons of instrumented ice at depths between 1.5 and 2.5 kilometers. below the surface of Antarctica, near the South Pole.
This unique telescope, which explores the far reaches of our universe using neutrinos, reported the first observation of a high-energy astrophysical neutrino source in 2018. The source, TXS 0506+056, is a known blazar located off the left shoulder of the Earth. Orion constellation and 4,000 million light years away.
“A single neutrino can identify a source. But only an observation with multiple neutrinos will reveal the hidden core of the most energetic cosmic objects,” says Francis Halzen, professor of physics at the University of Wisconsin-Madison (United States) and IceCube Principal Investigator.
The expert adds that “IceCube has accumulated about 80 neutrinos of teraelectronvolt energy coming from NGC 1068, which are not yet enough to answer all our questions, but they are definitely the next big step towards the realization of neutrino astronomy.”
Unlike light, neutrinos can escape in large numbers from extremely dense environments in the universe and reach Earth undisturbed by the matter and electromagnetic fields that permeate extragalactic space.
Although scientists imagined neutrino astronomy more than 60 years ago, the weak interaction of neutrinos with matter and radiation makes their detection extremely difficult. Neutrinos could be the key to our questions about the workings of the most extreme objects in the cosmos.
“Answering these far-reaching questions about the universe we live in is a primary goal of the US National Science Foundation,” says Denise Caldwell, director of the Physics Division at NSF.
Like the Milky Way, NGC 1068 is a barred spiral galaxy, with loose arms and a relatively small central bulge. Unlike the Milky Way, however, NGC 1068 is an active galaxy in which most of the radiation is not produced by stars, but is due to material falling into a black hole millions of times more massive. than our Sun and even more massive than the dormant black hole at the center of our galaxy.
NGC 1068 is an active galaxy, Seyfert II type in particular, seen from Earth at an angle that obscures its central region where the black hole is located. In a Seyfert II galaxy, a toroid of nuclear dust hides most of the high-energy radiation produced by the dense mass of gas and particles slowly spiraling toward the center of the galaxy.
“Recent models of the black hole environments in these objects suggest that gas, dust, and radiation should block gamma rays that would otherwise accompany neutrinos,” said Hans Niederhausen, a postdoctoral associate at the University Michigan State and one of the lead analysts on the work — this detection of neutrinos from the nucleus of NGC 1068 will improve our understanding of the environments surrounding supermassive black holes.”
NGC 1068 could become a standard candle for future neutrino telescopes, according to Theo Glauch, a postdoctoral associate at the Technical University of Munich (TUM) in Germany and another lead analyser.
“It is already a well-studied object by astronomers, and neutrinos will allow us to see this galaxy in a totally different way. A new view will certainly bring new insights,” he says.
According to Ignacio Taboada, a professor of physics at the Georgia Institute of Technology and spokesperson for the IceCube Collaboration, these results represent a significant improvement over a previous study on NGC 1068 published in 2020.
“Part of this improvement is due to improved techniques and another part to a careful updating of the detector calibration,” Taboada stresses. neutrinos to pinpoint NGC 1068 and make this observation possible.
Resolution of this source was made possible by improved techniques and refined calibrations, a result of the IceCube Collaboration’s hard work.” The improved analysis points the way to superior neutrino observatories already underway. “This is great news for the future of our field,” says Marek Kowalski, IceCube collaborator and Principal Scientist at Deutsches Elektronen-Synchrotron in Germany.
“It means that with a new generation of more sensitive detectors there will be a lot to discover,” he continues. “The future IceCube-Gen2 observatory could not only detect many more of these extreme particle accelerators, but also allow them to be studied at even higher energies.” It’s like IceCube giving us a map to a hidden treasure.”
With neutrino measurements from TXS 0506+056 and NGC 1068, IceCube is one step closer to answering the centuries-old question about the origin of cosmic rays. Furthermore, these results imply that there may be many more similar objects in the universe yet to be identified.