What invisible object weighs 20 million times as much as the Sun, travels through space at speeds greater than 1,500 kilometers per second, and leaves a long star trail in its wake? If you guessed “black hole”, you’re probably right. At least that’s the conclusion of an international team of researchers who used some of the world’s most powerful telescopes to find and study runaway candidates. Astrophysics Journal Letter.
For reasons that are still not well understood, supermassive black holes lurk at the center of most large galaxies, such as the Milky Way. Despite their frightening size, these mysterious giants are usually very dull and easily overlooked. They often only outwit their existence with the celestial fireworks they create while swallowing vast amounts of gas and dust from their host galaxy.
All of this makes supermassive black holes that somehow “go rogue” a strange and elusive breed. How do they escape their galactic hosts, and how can they be seen when they don’t emit any light? Only a handful of potential nomadic herders have been identified, but none are more convincing than the newly discovered fugitive, according to the study’s authors.
The black hole was discovered by accident when it first appeared as a faint streak in observations of globular clusters by the Hubble Space Telescope. Such features are usually artifacts of cosmic rays hitting Hubble’s detectors, explains Yale University astronomer and principal investigator Peter Van Dokkum. Further observations by the ground-based WM Keck Observatory on Mauna Kea, Hawaii, instead reveal the streak to be a staggering stream of young blue stars stretching over 200,000 light-years.
That stellar stream is the telltale sign, says Van Dokkum. It’s probably a sort of space contrail that originated from a source of gas that a charging black hole impacted and compressed into the star. It has arrowed back to the source galaxy, and now shows no sign of hiding a massive, feasting black hole at its center. “It has long been hypothesized that all galaxies are embedded in huge reservoirs of hydrogen gas,” says van Dokkum. “We see a black hole illuminating its gas as it speeds away, giving us a rare view of this elusive matter.”
“The age of these stars suggests that the black hole escaped about 40 million years ago and is zipping through space at a very high speed of about 1,600 kilometers per second,” he adds.
This speed excites many experts. “If this is a runaway black hole… it’s moving.” very Christopher Reynolds, professor of astronomy at Cambridge University, was not involved in the study. very fast, in fact, no Massive black holes scurrying wildly between galaxies seem unlikely.
Still, astronomers hope further observations with NASA’s James Webb Space Telescope and Chandra X-ray Observatory will clear up lingering questions. “We need more data to pinpoint this hypothesis,” says study co-author Maria Luisa Her Ph.D. Buzzo. She is a candidate at Swinburne University of Technology, Australia. “Additional data are needed to confirm this scenario and reduce uncertainty about its nature. [stellar stream] function,” she says. Astronomer Erin Bonning of Emory University, who was not involved in the study, agrees. “You’d want to see the direct gravitational effects of compact, massive objects,” she says.
Effects like these are important in the first place for explaining how something weighing millions or billions of the sun is expelled from the galaxy. We have long known that we can grow from collisions and coalescence. Giant galaxies can also merge with each other, bringing the black holes at their centers closer together. “You never know what’s going to happen next,” says van Dokkum. “More than 50 years ago, it was proposed that these black holes could move from their centers in aftereffects, or even pop out of the galaxy entirely. This observation seems to support that idea. It gives us insight into what happens when the most amazing objects in the universe come together.”
If two black holes were locked in a gravitational dance, and a third collided, the resulting instability could throw one of the trios with enough velocity to leave the host galaxy entirely. . Another possibility is that instead of three black holes dispersing each other like in billiards, two come together and he becomes one. “The second channel involves two black holes merging and releasing gravitational energy. [waves]says Harvard University astrophysicist Avi Loeb, who was not involved in the paper. “When they run into each other, [gravitational waves] In the general case where two black holes do not have the same mass, they have a preferred direction. As a result, the remnants of the merger recoil in the opposite direction to maintain momentum. ”
How exactly supermassive black holes can reach intergalactic space could have important implications for the host galaxies they leave behind. For example, black holes can either inhibit or promote further star formation. Finding more galaxies twirling the universe will give researchers powerful new tools to learn how galaxies are born, grow, and eventually die. Interesting details about this latest candidate happened to be spied on as a starry “scratch” in Hubble images, and Bonning and other experts believe that evidence of other similar escapees already exists and is yet to be discovered. I’m starting to suspect that it has gone unnoticed and is awaiting discovery in other datasets.
“If this is what’s really going on, and this is common enough, you just need to systematically search for this sort of thing,” says Bonning. Future panoramas from future facilities such as NASA’s Nancy Grace Roman Space Telescope and the ground-based Vera C. Rubin Observatory. A treasure trove can be revealed. , “A Needle in an Invisible Haystack”.
