Supermassive black holes at the centers of active galaxies might be significant sources of the universe’s high-energy neutrinos. Recent research using data from IceCube, the leading neutrino observatory situated in Antarctica, has pinpointed a common type of active galaxy, known as Seyfert galaxies, as likely neutrino producers. These discoveries, published in Physical Review Letters and on arXiv.org, strengthen the hypothesis that the cores of these active galaxies could be the primary sources of cosmic neutrinos observed throughout the universe.
According to astronomer Andrii Neronov from the Astroparticle and Cosmology Laboratory in Paris, these active galaxies are now seen as major contributors to the neutrino flux. Neronov expresses confidence in this hypothesis based on the current data.
This perspective marks a significant shift from just a few years ago. In 2022, the identification of Seyfert galaxy NGC 1068 as a likely source of high-energy neutrinos was unexpected, as many astronomers previously doubted such galaxies could produce neutrinos. However, new evidence indicates that neutrinos are also emanating from two other Seyfert galaxies, NGC 4151 and NGC 3079. This reinforces the idea that active galaxies, characterized by their supermassive black holes’ cores emitting vast amounts of energy (known as active galactic nuclei), are indeed capable neutrino producers.
The emergence of active galactic nuclei as sources of high-energy neutrinos is an exciting development for astrophysicists. These active galactic nuclei, particularly those obscured by dust and gas, are now being recognized as significant neutrino sources. This insight comes from a recent study coauthored by astrophysicist Sreetama Goswami of the University of Nevada at Las Vegas, highlighted in a June 10 preprint on arXiv.org submitted to Astrophysical Journal Letters.
The new findings contribute to a growing body of theoretical research aimed at identifying the origins of cosmic neutrinos. For example, a study accepted by Nature Astronomy and published as a preprint on May 30 pinpointed the area around the central supermassive black hole in NGC 1068 as the likely production site for neutrinos within that galaxy. If similar findings for NGC 4151 and NGC 3079 are confirmed, it would suggest that their high-energy particles are also generated near their central black holes.
Previously, only one other significant extragalactic neutrino emitter, a blazar, had been confidently identified. Blazars, which are also active galaxies, produce neutrinos in their massive jets of supercharged material. However, recent insights suggest that the black hole at the center of a blazar might ultimately be responsible for the neutrino production.
Francis Halzen, the principal investigator of IceCube and coauthor of the recent study, posits that dense cores, rather than jets, are the primary neutrino producers. This could include Seyfert galaxies, flat-spectrum radio quasars (a type of blazar), or any other galaxy with an obscured black hole.
Kohta Murase, a theoretical physicist at Penn State University, has extensively researched the origins of neutrinos from NGC 1068. He has long believed that the supermassive black holes’ centers of these galaxies are likely sources of neutrinos. Murase suggests that the corona, a very hot region surrounding the black hole, is a promising site for neutrino production. Understanding this region could provide insights into the physical properties of the corona.
Astronomers are also examining which types of active galaxies are the most significant neutrino producers. There is ongoing debate about whether jetless active galactic nuclei, such as Seyfert galaxies, could be responsible for nearly all extragalactic neutrinos, or if blazars are necessary to explain the highest-energy neutrinos. It’s also possible that there are other, yet-to-be-identified sources of neutrinos.
While there is a general consensus among astronomers that active galaxies with supermassive black holes are major sources of high-energy neutrinos, the extent of their contribution is still uncertain.
- ONLINE NEWS Johnson-Groh, M. (2024, June 26). We may finally know the source of mysterious high-energy neutrinos. Science News. [Science News]
- JOURNAL Abbasi, R., Ackermann, M., Adams, J., Agarwalla, S. K., Aguilar, J. A., Ahlers, M., Alameddine, J. M., Amin, N. M., Andeen, K., Argüelles, C., Ashida, Y., Athanasiadou, S., Ausborm, L., Axani, S. N., Bai, X., V, A. B., Baricevic, M., Barwick, S. W., Bash, S., . . . Zimmerman, M. (2024). Search for neutrino emission from hard X-ray AGN with IceCube. arXiv (Cornell University). [arXiv.org]
- JOURNAL Murase, K. (2022). Hidden hearts of neutrino active galaxies. The Astrophysical Journal Letters, 941(1), L17. [The Astrophysical Journal Letters]
- JOURNAL Murase, K., Karwin, C. M., Kimura, S. S., Ajello, M., & Buson, S. (2024). Sub-GeV Gamma Rays from Nearby Seyfert Galaxies and Implications for Coronal Neutrino Emission. The Astrophysical Journal Letters, 961(2), L34. [The Astrophysical Journal Letters]
- JOURNAL Neronov, A., Savchenko, D., & Semikoz, D. V. (2024). Neutrino Signal from a Population of Seyfert Galaxies. Physical Review Letters, 132(10). [Physical Review Letters]
- JOURNAL Padovani, P., Resconi, E., Ajello, M., Bellenghi, C., Bianchi, S., Blasi, P., Huang, K.-Y., Gabici, S., Gámez Rosas, V., Niederhausen, H., Peretti, E., Eichmann, B., Guetta, D., Lamastra, A., & Shimizu, T. (2024). Supermassive black holes and very high-energy neutrinos: the case of NGC 1068. arXiv (Cornell University). [arXiv.org]
APA 7: TWs Editor. (2024, June 26). Supermassive Black Holes as Neutrino Factories: Mystery Solved!. PerEXP Teamworks. [Online News Link]
