Two known black holes are spinning too quickly to have ever been impacted by the hypothetical particle known as ultralight bosons, proving that, between two certain masses, the particles don’t exist, according to new research by an MIT astrophysicist.
“It’s a proof by contradiction. If they did exist, we should not have seen this, [but] since we saw this very large angular momentum, they don’t exist,” said Salvatore Vitale, who works at MIT’s Laser Interferometer Gravitational-Wave Observatory, or LIGO.
Ultralight bosons are a hypothetical particle theorized to be one-billionth the mass of an electron and likely a form of dark matter — “the mysterious, invisible stuff that makes up 85 percent of the matter in the universe,” according to an MIT News post. Joining Vitale on the research were Ken K.Y. Ng, Otto A. Hannuksela, and Tjonnie G.F. Li. The work was published in Physical Review Letters, a scientific journal.
The researchers used black holes to search for ultralight bosons as quantum theory dictates that all black holes over a certain mass should have relatively slow spins, a result of pulling in clouds of electric bosons which would slow the black holes’ motion. But, they found that the two black holes they were observing were spinning at too high a rate of speed to have been impacted by the bosons.
That conclusion led the team to rule out the existence of ultralight bosons with masses between 1.3x10⁻¹³ electronvolts and 2.7x10⁻¹³ electronvolts.
Vitale explained the research and ensuing conclusion with the analogy of a spinning carousel.
“The idea is that if you have something that rotates, like a carousel ... you can show that if you either jump or throw something at the carousel while it’s rotating. If then, a piece of the thing that you throw at it falls out from the carousel, it can come back out with more energy than what it had before it hit the carousel,” Vitale said in a telephone interview. “It’s extracting energy from the carousel. So, you throw something with very low energy, and it comes back at you with more energy than it had before ... you just slow it down a bit from his rotational velocity.”
Vitale said the findings could help researchers solve a number of open questions in the field of particle physics.
“In reality, there is a much broader set of theories that predict or relies on the existence of these very ultra-light particles. One is dark matter. So they could be dark matter. But they could also solve other open problems in particle physics,” he said.
These findings will allow researchers to further their quest to prove the existence of dark matter by expanding the range of particles they observe, Vitale said.
“We will never stop exploring,” he said.
Vitale said his work in the field began as a post-doc in 2012, and he marveled at the rapid expansion of the knowledge base in astrophysics — noting that the first gravitational wave discovered by humans was found in 2015.
“I think it’s incredible, really, in five years we went from this happening for the first time ever, to now we’re gonna get one new source every week,’' he said.