A huge cloud of misshapen dust that astronomers have dubbed “the Tadpole” could point to the location of an extremely rare type of black hole never before confirmed in our galaxy.
In a study published January 10 in The Astrophysical Journal (opens in new tab)researchers from Japan describe the strange cloud of dust, which looks like a tadpole with a big head and a long tail and lies near the center of the Milky Way in the constellation of Sagittarius, about 27,000 light years from Earth.
This region of the Milky Way, known as the Central Molecular Zone, is extremely dense with the star-forming dust clouds that cluster around our galaxy. central supermassive black hole, known as Sagittarius A*. Even in this extreme environment, the tadpole’s shape and movement stood out to the researchers.
Using observations from the James Clerk Maxwell Telescope in Hawaii, as well as the 45 m Nobeyama Radio Telescope in Nagano, Japan, the team analyzed the Tadpole and its surrounding environment at various wavelengths. The researchers determined that Tadpole was being stretched into its unusual shape by the intense gravitational pull of a nearby object. However, no matter what wavelengths they looked at, the team’s search turned up no signs of anything massive enough to cause such a warp.
This glaring absence revealed a major clue as to the identity of the unseen object.
“Tadpole’s spatial compactness and absence of bright counterparts at other wavelengths indicate that the object may be an intermediate-mass black hole,” the researchers wrote in the study.
Related: What happens at the center of a black hole?
black holes are so massive that nothing, not even light, can escape the pull of their gravity, so astronomers cannot see them directly. However, researchers can identify black holes based on the way these cosmic monsters deform space and objects Around them.
Most black holes discovered to date fall into two categories: stellar-mass black holes, which can weigh up to 100 times the mass of Earth’s sun and form when massive stars collapse under their own weight; and supermassive black holes, which lie at the center of nearly all large galaxies and can be millions to billions of times more massive than the sun. Scientists are still not sure how the universeSupermassive black holes formed.
Between these two categories is an elusive third type of black hole: intermediate-mass black holes. These objects, which can measure between 100 and 100,000 solar masses, are considered a “lost link” in black hole theory, as their average size may represent a crucial growth stage between smaller and supermassive black holes.
So far, only a handful of intermediate-mass black hole candidates have been identified in the entire universe. None have ever been proven to exist in the Milky Way, although several candidates have been spotted, including four others near the galactic center.
When the study authors calculated the mass needed to stretch the Tadpole into its distinctive shape, they found that a black hole measuring approximately 100,000 solar masses was the most likely culprit.
While the discovery requires more observations to confirm, the existence of one more potential intermediate-mass black hole near the Galaxy‘s center suggests they may be more abundant there than astronomers previously thought. This gives future researchers a promising target to study in their search for one of the most massive missing links in the universe.