‘Runaway’ black hole mystery solved: What is the ‘invisible monster?’
Scientists have solved the mystery behind the “runaway” black hole tearing through the universe, which was discovered last month and quickly dubbed an “invisible monster on the loose.”
A new study published in the journal Astronomy & Astrophysics suggested that what was thought to be a supermassive black hole creating a never-before-seen trail of stars was actually a “bulgeless galaxy viewed edge-on.”
A “bulgeless” galaxy lacks a large collection of stars at its center, according to NASA.
This revelation by researchers at the Instituto de Astrofísica in the Canary Islands challenges the thought that a black hole was pushing into gas in front of it to create the new star formation in a narrow corridor — rather than eating up the stars ahead of it, leaving behind a 200,000-light-year-long “contrail” of newborn stars twice the diameter of the Milky Way.
“There’s an invisible monster on the loose, barreling through intergalactic space so fast that if it were in our solar system, it could travel from Earth to the moon in 14 minutes,” NASA wrote in a release last month.
Astronomers believed the runaway black hole discovered by the Hubble Space Telescope was set free after two galaxies merged about 50 million years ago — which brought together two supermassive black holes at their centers. Then a third galaxy came with its own supermassive black hole, and the three combined to form a “chaotic and unstable configuration.”
Researchers from Yale University thought one of the black holes gained momentum from the other two and escaped out of its host galaxy, while the other two took off in the opposite direction.
“We think we’re seeing a wake behind the black hole where the gas cools and is able to form stars. So, we’re looking at star formation trailing the black hole,” Pieter van Dokkum of Yale University said. “What we’re seeing is the aftermath. Like the wake behind a ship, we’re seeing the wake behind the black hole.”
Now, researchers suggest the mystery trail of stars is actually a common type of galaxy, just viewed from a different angle.
“The motions, the size, and the quantity of stars fits what has been seen in galaxies within the local universe,” lead author Jorge Francisco Sánchez Almeida said in a statement.
“It’s a relief to have found the solution to this mystery, the new proposed scenario is much simpler. In one sense it is also a pity, because the existence of fleeing black holes is expected, and this could have been the first one to be observed.”
Researchers compared the never-before-seen trail of stars with a more well-known bulgeless galaxy: IC5249.
This galaxy and the mysterious “black hole” have a similar mass of stars that moved in similar ways.
“When we analyzed the velocities of this distant structure of stars, we realized that they were very similar to those obtained from the rotation of galaxies, so we decided to compare a much closer galaxy, and found that they are extraordinarily similar,” study co-author Mireia Montes said.
Ignacio Trujillo, an IAC researcher who worked on the study, added: “We also looked at the relation between the mass of the assumed galaxy and its maximum velocity of rotation, and discovered that indeed it is a galaxy which behaves like a galaxy.”
“It is an interesting object, because it is quite a large galaxy at a very large distance from Earth, where the majority of the galaxies are smaller.”
