Fans of J.R.R. Tolkien’s “The Lord of the Rings” books or those who enjoyed Peter Jackson’s Oscar-winning movie versions of the story will be familiar with the Eye of Sauron. It was the name given to the way the primary antagonist of the story, Sauron, watched his war unfold and searched for the One Ring. Mounted at the top of Barad-dûr, the eye resembled a black hole surrounded by flame.
A new discovery brought this villain to mind when a team of researchers was trying to understand how powerful jets from blazars can accelerate particles to extremely high energies, producing both gamma rays and neutrinos. Their findings were published in the Astronomy & Astrophysics journal under the title “Looking into the jet cone of the neutrino-associated very high-energy blazar PKS 1424+240” on August 12, 2025.
In this study, the researchers focused on a blazar called PKS 1424+240 (blazar is a term for a galaxy powered by a black hole). The blazar they studied looked very similar to the Eye of Sauron, and their research into it can help to explain what is referred to as the Doppler factor crisis.
How the Eye of Sauron black hole was named
The blazar chosen had always been a source of fascination because of how bright it is and its high-energy gamma rays. However, its radio jet moved more slowly than scientists expected based on its brightness. The term radio jet here refers to jets of energy that shoot out from the poles of the black hole.
To help understand the contradiction, the researchers analyzed 15 years’ worth of images of this jet and utilized very long baseline interferometry, also referred to as VLBI. This technique connects worldwide radio telescopes into a single image, resulting in an improved resolution. Because the jet was pointed directly at Earth, the researchers were able to get a better look inside of it to improve their understanding of its shape and magnetic field.
With this enhanced view of the black hole, the resemblance to Tolkien’s epic fantasy story was apparent. It is stated in the publication, “We call the image (after J. R. R. Tolkien) ‘the Eye of Sauron’ because its nature is striking and resembles the illustrator’s (Alan Lee) views of the villain in the ‘Lord of the Rings’.” That is definitely an easy visual to remember.
How this impacts the future of black hole studies
Scientists believe that supermassive and ultramassive black holes at the center of distant galaxies are some of the most powerful particle accelerators in the universe. It was still not fully understood, though, how particles in these jets reach such extreme energies. This puzzle is referred to as the Doppler factor crisis, where scientists see slow jet motion in radio observations, yet the energy emitted suggests faster speeds.
In studying the Eye of Sauron, the alignment toward Earth makes the jet appear brighter and more energetic due to a strong boosting effect called relativistic beaming. They also found evidence of a twisted magnetic field, meaning the jet is carrying an electric current. Both of these solve the Doppler factor crisis by showing that jets can emit both gamma rays and neutrinos more efficiently when viewed head-on. In other words, how we view the jets influences the signals we detect from them.
It is believed that only a small percentage of blazars are aligned in the same way as the Eye of Sauron. And blazars like the Eye of Sauron that allow researchers to view their cores are a rare and valuable opportunity to learn more about our universe. The researchers hope that their study can be applied to similar jets to find out if they all share these same characteristics.
