- A NASA Hubble image may show the first runaway supermassive black hole ever discovered.
- A trail showing an object traveling away from a galaxy suggests that a black hole was ejected.
- A rogue black hole may have created a shock wave that made a trail of new stars visible in the image.
The Hubble Space Telescope is still making first-of-its-kind discoveries after more than three decades in space. His latest? Observations of the first supermassive black hole to disappear from its own galaxy.
That’s what a team of astronomers suggests in a new study published online. The study has been peer-reviewed for publication in the Astrophysical Journal Letters, according to Pieter van Dokkum, an astrophysicist at Yale University who led the new study.
Even experts not involved in the study are excited about the team’s results.
“The observations all fit together with this scenario,” Manuela Campanelli, an astrophysicist at the Rochester Institute of Technology who is not involved in the study but has simulated black holes in her research, told Insider.
The first possible photo of a “rogue” supermassive black hole
What you see above are two images of the same thing that tell the story of what happened.
Look at the zoomed-in shot on the right: The big spot in the upper right is a galaxy. Then follow the faint line that follows away from it, ending at a point on the lower left. That’s where scientists believe the runaway black hole is hiding.
Black holes, by their very nature, are invisible. The reason astronomers are able to “see” any black hole is because it is surrounded by a swirling hot disk of gas, stars, and other cosmic elements that are visible.
But the most fascinating part of these photos is the sequence you see trailing behind the black hole. This caught the eye of researchers as they examined nearby stars.
They believe the long tail coming out of the black hole is actually a trail of newborn stars, which formed after the black hole was ejected from its galaxy and hurtled through space, creating a shock wave that caused clouds of intergalactic gas to collapse into stars . .
“I thought I had really made a mistake that there was this weird streak in the picture,” van Dokkum told Insider. “It didn’t look like any astrophysical object at first. And then it turned out to be real. It was also in other data sets. And that’s when I got excited.”
Although black holes are notorious for devouring and destroying stars, this one appears to be creating them as well.
Further observations, possibly with the James Webb Space Telescope, are needed to confirm that the object in the image is indeed a runaway supermassive black hole.
Because a supermassive black hole would be ruthless
Supermassive black holes are incredibly dense objects with the mass of billions of suns, and scientists believe there is one at the center of every galaxy. Needless to say, kicking someone out of their home would take a lot of strength.
One such cataclysmic event that could potentially do the job is if two galaxies collide and their central black holes merge. A collision between black holes is one of the most violent, powerful events in the universe and could send a smaller black hole remnant into the void.
Astrophysicists have long theorized that black holes could “cheat,” or “run away,” if other black holes pushed them out of their galaxies.
But no one has ever confirmed a black hole wandering through intergalactic space, much less a oversize black hole going rogue.
And while two galaxies colliding is the simplest explanation for a rogue black hole, that doesn’t seem to have happened here.
2 other black holes may have ejected it in a rare, violent event
Van Dokkum believes this black hole had a particularly rare, dramatic, violent exit. Here’s his theory: Two galaxies merged and their supermassive black holes fell together, due to their sheer gravitational pull.
This happens all the time. Hubble has photographed many merging galaxies like the ones in the image below. The next step is what made this merger so strange.
The team believes that a third galaxy arrived, with a third black hole, and its gravity caused a complex dance of the three black holes, which ended with one of them being ejected into the distance.
Since then, over a period of 39 million years, the runaway black hole has been screaming away from its home galaxy at about 1,600 kilometers (nearly 1,000 miles) per second, according to van Dokkum’s team’s calculations. For reference, at that speed it would take you 25 seconds to circle the entire Earth.
Basically, this supermassive black hole (if that’s what it is) became a third wheel and was kicked out of its home. Evidence for this third galaxy has yet to be confirmed, but the team is investigating a trail that faces the opposite side of the galaxy, where they believe the other two black holes merged and were then ejected by the recoil.
“The picture really tells the story,” van Dokkum said.
That makes this event extremely rare, Campanelli said, because it involved three black holes instead of the conventional two that theorists usually posit in a scenario like this.
Follow the tracks of newborn stars — if they’re not just a jet
The other explanation for the mysterious trail in van Dokkum’s Hubble photo is a fairly common one: jets of material ejected from the centers of galaxies with highly active black holes.
But van Dokkum and Campanelli both say that’s unlikely, based on the shape of the path in the new image. Jets shooting from galactic centers disappear away from the galaxy as material is ejected from one point and spreads out into the distance, as seen in the Hubble image below:
Instead, the trail in van Dokkum’s Hubble image marvels to the galaxy. It appears to be a trail of new stars formed as the traveling black hole created shock waves in the intergalactic gas.
Campanelli added that the galaxy’s compact and irregular shape is “typical” of galaxies formed by mergers.
“If it turns out not to be true, I would be surprised,” van Dokkum said. “If it’s not real, I think it’s actually a combination of some other gas clouds or something that seemed to be aligned in such a way that it looks like a line.”
Even though they are invisible, there is no need to worry about rogue supermassive black holes being hidden from us by other galaxies.
“We would have seen the effects of it if it was anywhere near us,” van Dokkum said.