A huge, deformed cloud of dust that astronomers have dubbed “the tadpole” could point to the location of an extremely rare type of black hole that has never before been confirmed to exist in our galaxy.
In a study published on 10 January i The Astrophysical Journal (opens in a new tab)Japan-based scientists describe the strange dust cloud, which looks like a large-headed, long-tailed tadpole and sits near the center of The Milky Way in the constellation Sagittarius, approximately 27,000 light years from Earth.
This region of the Milky Way, known as the Central Molecular Zone, is extremely dense with star-forming dust clouds clumping 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 Nobeyama 45-m radio telescope in Nagano, Japan, the team analyzed the tadpole and its environment at multiple wavelengths. The researchers determined that the tadpole was stretched into its unusual shape by the intense gravitational pull of a nearby object. But whatever wavelengths they looked at, the team’s search revealed no sign of anything massive enough to cause such a deformation.
This glaring absence revealed a major clue about the invisible object’s identity.
“The spatial compactness of the tadpole and the 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 in the center of a black hole?
Black holes are so massive that nothing, not even light, can escape their pull gravity, so astronomers cannot see them directly. However, scientists can identify black holes based on the way these cosmic monsters distort 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 sit at the center of almost all large galaxies and can be millions to billions of times more massive than the Sun. Scientists are still not sure how universe‘s supermassive black hole formed.
Between these two categories is an elusive third type of black hole: medium-sized black holes. These objects, which can measure between 100 and 100,000 solar masses, are considered a “missing link” in black hole theory, as their intermediate size may represent a crucial growth stage between smaller black holes and supermassives.
So far, only a handful of intermediate-mass black hole candidates have been identified across the universe. None have ever been proven to exist in the Milky Way, although several candidates have been discovered, including four others near the galactic center.
When the study authors calculated the mass required to stretch the tadpole into its distinct shape, they found that a black hole measuring roughly 100,000 solar masses was the most likely culprit.
Although the finding requires further observations to confirm, another potential intermediate-mass black hole exists nearby galaxythe center suggests they may be more abundant there than astronomers previously thought. This gives future scientists a promising target to study in their search for one of the universe’s most massive missing links.