First take a look at the inner depths of an active galaxy provided by ghostly neutrinos



Hubble image of spiral galaxy NGC 1068. Credit: NASA / ESA / A. van der Hoeven

An international team of scientists has for the first time detected evidence of a high-energy neutrino emission from the galaxy NGC 1068. NGC 1068, also known as Messier 77, was first observed in 1780. active galaxy In the constellation Cetus it is one of the most famous and well-studied galaxies to date. This galaxy is located 47 million light-years away from us, and can be seen with a large telescope. The results will be published today (November 4, 2022) in the journal SciencesYesterday, she participated in a scientific webinar that brought together experts, journalists and scientists from all over the world.

Physicists often refer to the neutrino as a “ghost particle” because they never interact with other matter.

The discovery was made at the IceCube Neutrino Observatory. This huge neutrino telescope, powered by the National Science Foundation, includes a billion tons of processed ice at depths ranging from 1.5 to 2.5 kilometers (0.9 to 1.2 miles) below the surface of Antarctica near the South Pole. This unique telescope explores the farthest reaches of our universe using neutrinos. I reported the first observation of a A high-energy astrophysical neutrino source In 2018. The source is a well-known blazar named TXS 0506 + 056 located 4 billion light-years from the left shoulder of the constellation Orion.

A single neutrino can determine the source. Just observing multiple neutrinos will reveal the mysterious core of the most energetic cosmic objects, says Frances Halzen, professor of physics at the University of Wisconsin-Madison and principal investigator at IceCube. “IceCube has collected about 80 tera-electronvolt neutrinos from NGC 1068, which is not yet enough to answer all our questions, but it is certainly the next big step toward achieving neutrino astronomy,” he adds.

Ice Cube Neutrino Detector

When neutrinos interact with particles in clear Antarctic ice, they produce secondary particles that leave a trail of blue light as they travel through the IceCube detector. Credit: Nicolle R. Fuller, IceCube/NSF

Unlike light, neutrinos can escape in large numbers from highly dense environments in the universe and reach Earth undisturbed by matter and the electromagnetic fields that permeate extragalactic space. Although scientists conceived neutrino astronomy more than 60 years ago, the weak interaction of neutrinos with matter and radiation makes them extremely difficult to detect. Neutrinos could be key to our questions about how the most extreme objects in the universe work.

“Answering these far-reaching questions about the universe we live in is a primary focus of the US National Science Foundation,” says Dennis Caldwell, director of the US National Science Foundation’s Department of Physics.

This video shows how IceCube neutrinos gave us our first glimpse into the inner depths of the active galaxy, NGC 1068. Credit: Video by Diogo da Cruz, voiced by Falun Mayanga and by Georgia Kao.

As with our home galaxy, the[{” attribute=””>Milky Way, NGC 1068 is a barred spiral galaxy, with loosely wound arms and a relatively small central bulge. However, unlike the Milky Way, NGC 1068 is an active galaxy where most radiation is not produced by stars but due to material falling into a black hole millions of times more massive than our Sun and even more massive than the inactive black hole in the center of our galaxy.

NGC 1068 is an active galaxy—a 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 torus of nuclear dust obscures most of the high-energy radiation produced by the dense mass of gas and particles that slowly spiral inward toward the center of the galaxy.

Messier 77 and Cetus

Messier 77 and Cetus in the sky. Credit: Jack Parin, IceCube/NSF; NASA/ESA/A. van der Hoeven (insert)

“Recent models of the black hole environments in these objects suggest that gas, dust, and radiation should block the gamma rays that would otherwise accompany the neutrinos,” says Hans Niederhausen, a postdoctoral associate at Michigan State University and one of the main analyzers of the paper. “This neutrino detection from the core of NGC 1068 will improve our understanding of the environments around 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 main analyzer.

IceCube Detector Schematic

IceCube detector schematic showing the layout of the strings across the ice cap at the South Pole, and the active detection array of light sensors filling a cubic kilometer volume of deep ice.

“It is already a very well-studied object for astronomers, and neutrinos will allow us to see this galaxy in a totally different way. A new view will certainly bring new insights,” says Glauch.

These findings represent a significant improvement on a prior study on NGC 1068 published in 2020, according to Ignacio Taboada, a physics professor at the Georgia Institute of Technology and the spokesperson of the IceCube Collaboration.

IceCube Neutrino Scientists

From left to right: Martin Wolf (TUM), Hans Niederhausen (TUM), Elisa Resconi (TUM), Chiara Bellenghi (TUM), Francis Halzen (UW–Madison), and Tomas Kontrimas (TUM). Credit: Yuya Makino, IceCube/NSF

“Part of this improvement came from enhanced techniques and part from a careful update of the detector calibration,” says Taboada. “Work by the detector operations and calibrations teams enabled better neutrino directional reconstructions to precisely pinpoint NGC 1068 and enable this observation. Resolving this source was made possible through enhanced techniques and refined calibrations, an outcome of the IceCube Collaboration’s hard work.”

The improved analysis points the way toward superior neutrino observatories that are already in the works.

“It is great news for the future of our field,” says Marek Kowalski, an IceCube collaborator and senior scientist at Deutsches Elektronen-Synchrotron, in Germany. “It means that with a new generation of more sensitive detectors there will be much to discover. The future IceCube-Gen2 observatory could not only detect many more of these extreme particle accelerators but would also allow their study at even higher energies. It’s as if IceCube handed us a map to a treasure trove.”

IceCube Collaboration Spring 2022

The IceCube Collaboration, spring 2022. Credit: IceCube Collaboration

With the neutrino measurements of TXS 0506+056 and NGC 1068, IceCube is one step closer to answering the century-old question of the origin of cosmic rays. Additionally, these results imply that there may be many more similar objects in the universe yet to be identified.

“The unveiling of the obscured universe has just started, and neutrinos are set to lead a new era of discovery in astronomy,” says Elisa Resconi, a professor of physics at TUM and another main analyzer.

“Several years ago, NSF initiated an ambitious project to expand our understanding of the universe by combining established capabilities in optical and radio astronomy with new abilities to detect and measure phenomena like neutrinos and gravitational waves,” says Caldwell. “The IceCube Neutrino Observatory’s identification of a neighboring galaxy as a cosmic source of neutrinos is just the beginning of this new and exciting field that promises insights into the undiscovered power of massive black holes and other fundamental properties of the universe.”

Reference: “Evidence for neutrino emission from the nearby active galaxy NGC 1068” by IceCube Collaboration, R. Abbasi, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. Ahrens, J. M. Alameddine, C. Alispach, A. A. Alves, N. M. Amin, K. Andeen, T. Anderson, G. Anton, C. Argüelles, Y. Ashida, S. Axani, X. Bai, A. Balagopal V., A. Barbano, S. W. Barwick, B. Bastian, V. Basu, S. Baur, R. Bay, J. J. Beatty, K.-H. Becker, J. Becker Tjus, C. Bellenghi, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, G. Binder, D. Bindig, E. Blaufuss, S. Blot, M. Boddenberg, F. Bontempo, J. Borowka, S. Böser, O. Botner, J. Böttcher, E. Bourbeau, F. Bradascio, J. Braun, B. Brinson, S. Bron, J. Brostean-Kaiser, S. Browne, A. Burgman, R. T. Burley, R. S. Busse, M. A. Campana, E. G. Carnie-Bronca, C. Chen, Z. Chen, D. Chirkin, K. Choi, B. A. Clark, K. Clark, L. Classen, A. Coleman, G. H. Collin, J. M. Conrad, P. Coppin, P. Correa, D. F. Cowen, R. Cross, C. Dappen, P. Dave, C. De Clercq, J. J. DeLaunay, D. Delgado López, H. Dembinski, K. Deoskar, A. Desai, P. Desiati, K. D. de Vries, G. de Wasseige, M. de With, T. DeYoung, A. Diaz, J. C. Díaz-Vélez, M. Dittmer, H. Dujmovic, M. Dunkman, M. A. DuVernois, E. Dvorak, T. Ehrhardt, P. Eller, R. Engel, H. Erpenbeck, J. Evans, P. A. Evenson, K. L. Fan, A. R. Fazely, A. Fedynitch, N. Feigl, S. Fiedlschuster, A. T. Fienberg, K. Filimonov, C. Finley, L. Fischer, D. Fox, A. Franckowiak, E. Friedman, A. Fritz, P. Fürst, T. K. Gaisser, J. Gallagher, E. Ganster, A. Garcia, S. Garrappa, L. Gerhardt, A. Ghadimi, C. Glaser, T. Glauch, T. Glüsenkamp, A. Goldschmidt, J. G. Gonzalez, S. Goswami, D. Grant, T. Grégoire, S. Griswold, C. Günther, P. Gutjahr, C. Haack, A. Hallgren, R. Halliday, L. Halve, F. Halzen, M. Ha Minh, K. Hanson, J. Hardin, A. A. Harnisch, A. Haungs, D. Hebecker, K. Helbing, F. Henningsen, E. C. Hettinger, S. Hickford, J. Hignight, C. Hill, G. C. Hill, K. D. Hoffman, R. Hoffmann, B. Hokanson-Fasig, K. Hoshina, F. Huang, M. Huber, T. Huber, K. Hultqvist, M. Hünnefeld, R. Hussain, K. Hymon, S. In, N. Iovine, A. Ishihara, M. Jansson, G. S. Japaridze, M. Jeong, M. Jin, B. J. P. Jones, … J. P. Yanez, S. Yoshida, S. Yu, T. Yuan, Z. Zhang, P. Zhelnin, 3 November 2022, Science.
DOI: 10.1126/science.abg3395

The IceCube Neutrino Observatory is funded and operated primarily through an award from the National Science Foundation to the University of Wisconsin–Madison (OPP-2042807 and PHY-1913607). The IceCube Collaboration, with over 350 scientists in 58 institutions from around the world, runs an extensive scientific program that has established the foundations of neutrino astronomy.

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