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CAMBRIDGE, Mass. — Someone alert the Jedi; there really is a “Death Star” floating through deep space! It turns out that certain black holes act just like the terrifying sci-fi battle station, spinning around to fire giant beams at various targets in the cosmos. Astronomers working with NASA are actually calling these amazing gravity wells “Death Star black holes.” Now, they're getting a chance to actually see these supermassive spectacles in action.
The findings, in a nutshell:
Publishing their work in The Astrophysical Journal, scientists discovered that supermassive black holes at the centers of galaxies don't just fire powerful beams of particles in one direction for eternity. These cosmic beasts can actually swivel their beams almost 90 degrees over the course of a few million years — which is the blink of an eye for these objects, which can be over 10 billion years-old. Researchers from the Harvard-Smithsonian Center for Astrophysics compare it to the Death Star in “Star Wars” rapidly changing targets.
Why does this matter? These intense beams from black holes play a key role in regulating star formation in galaxies. They blast away clouds of hot gas, preventing that gas from cooling down enough to coalesce into new stars. So, when a black hole's beam shifts direction, it impacts different regions of its host galaxy, shutting down star birth over a much wider area. On cosmic scales, these Death Star black holes can drastically influence how many stars and planets form in the universe. In an amazing way, these black holes may actually be wiping out planets just like their fictional namesake!
How did scientists detect the beam shifts?
To uncover this behavior, astronomers used NASA's Chandra X-ray telescope to study 16 galaxies with supermassive black holes surrounded by hot gas. X-ray data revealed cavities or bubbles in this gas. These are signs of where the black hole's particle beams have pushed it outwards in the past.
By comparing the locations of large outer cavities to the current directions of the black holes' particle jets (detected using radio observations), the team could see if the beams were still pointing the same way. In about a third of cases, the jets were offset from the cavities by up to 90 degrees!
To rule out alternative explanations like gas sloshing around, the researchers looked for sloshing signatures in both aligned and misaligned systems. The presence of sloshing in both groups suggests it's likely not the sole cause of the directional changes. So, while the exact method for this movement is still unknown, it seems some black holes can completely reorient their powerful beams over millions of years, rapidly changing their galactic targets and widespread influence over which stars will live or die.
What do the researchers say?
“These Death Star black holes are swiveling around and pointing at new targets, like the fictional space station in Star Wars,” explains study leader Francesco Ubertosi of the University of Bologna in a media release.
“Considering that these black holes are likely more than 10 billion years old,” says co-author Gerrit Schellenberger of the Center for Astrophysics | Harvard & Smithsonian (CfA), “we consider a large change in direction over a few million years to be fast. Changing the direction of the giant black hole beams in about a million years is analogous to changing the direction of a new battleship in a few minutes.”
“These galaxies are too distant to tell if the beams from the Death Star black holes are damaging stars and their planets, but we are confident they are preventing many stars and planets from forming in the first place,” concludes co-author Ewan O’Sullivan, also from CfA.
