The universe is vast, making it extremely difficult to measure distances between heavenly bodies. Currently, the most common method can measure relative distances, but researchers from the Niels Bohr Institute at the University of Copenhagen, the University of Southampton, and the Kyoto Sangyo University have found another way thanks to "Eye of Sauron."
Officially, "Eye of Sauron" is known as NGC 4151. It earned its moniker for closely resembling the Great Eye that symbolized Sauron from The Lord of the Rings. It is a galaxy estimated to be 13 to 95 million light-years away from Earth. With the help of the twin telescopes at the W. M. Keck Observatory in Hawaii, researchers were able to narrow down the galaxy's distance to a more-accurate 62 million light-years.
Published in the journal Nature, the researchers' work entailed using the twin 32-foot telescopes to achieve a resolution 100 times better than what the Hubble Space Telescope is capable of. Thanks to that clarity, the researchers were able to see NGC 4151's center clearly as well as the infrared glow of the hot dust ring around the galaxy's black hole.
"Using telescopes on Earth, we can now measure the time delay between the ultraviolet light from the black hole and the subsequent infrared radiation emitted from the dust cloud," explained Darach Watson, associate professor at the Dark Cosmology Centre at the Niels Bohr Institute, University of Copenhagen.
The recorded time difference between the black hole's ultraviolet light and the resulting infrared radiation from the dust ring is around 30 days. Factoring in speed of light, the researchers were able to calculate for the distance between the black hole and the dust ring. Using that number as the base of a triangle, they were then able to determine the exact distance between NGC 4151 and Earth.
"One of the key findings is that the distance determined in this new fashion is quite precise - with 90 percent accuracy. In fact, this method, based on simple geometrical principles, gives the most precise distances for remote galaxies. Moreover, it can be readily used on many more sources than current methods," said Dr. Sebastian Hoenig from the University of Southampton, the study's lead author.
With the new technique Hoenig and colleagues came up with, it is now possible to measure distance between the Earth and about 10 percent of the active galaxies in the universe. This means being able to measure distances farther than the supernovas that proved that the universe is expanding at a rate that is accelerating.
