Rapidly rotating black holes reduce the search for particles of dark matter

Ultralight bosons are hypothetical particles whose mass is predicted to be less than one billionth of the mass of an electron. They have relatively little interaction with their environment and have so far evaded searches to confirm their existence. If it exists, ultra-light bosons like actions are likely to be a form of dark matter, the mysterious, invisible thing that makes up 85 percent of matter in the universe.

Now physicists from the MIG’s LIGO laboratory have been searching for ultralight forest zones using black holes – objects that are orders of magnitude larger than the particles themselves. According to the predictions of quantum theory, a black hole must draw a certain mass of clouds from ultralight forest zones, which in turn must slow down a black hole’s rotation. If the particles exist, all black holes of a given mass must have relatively low turns.

But physicists have found that two previously identified black holes rotate too fast to be affected by ultralight forest zones. Due to their large turn, the existence of the black holes excludes the existence of ultralight forest zones with a mass between 1.3×10^-13 electron volts and 2.7×10^-13 electron volts – about a quintillion of the mass of an electron.

The team’s results, released today in Physical overview letters, further reduces the search for actions and other ultralight forest zones. The study is also the first to use the rotation of black holes detected by LIGO and Virgo, using gravitational wave data to search for dark matter.

“There are different types of forest zones, and we have one investigation,” says co-author Salvatore Vitale, assistant professor of physics at MIT. “There may be others, and we can apply this analysis to the growing dataset that LIGO and Virgo will provide over the next few years.”

Vitale’s co-authors are lead author Kwan Yeung (Ken) Ng, a graduate student at MIT’s Kavli Institute for Astrophysics and Space Research, with researchers at Utrecht University in the Netherlands and the Chinese University of Hong Kong.

A carousel’s energy

Ultralight bush zones are sought in a wide range of superlight masses, from 1×10^-33 electron volts up to 1×10^-6 electron volts. Scientists have so far used tabletop experiments and astrophysical observations to exclude slips from this wide space of possible masses. Since the early 2000s, physicists have suggested that black holes may be another way to detect ultralight bosons, due to an effect known as super-radiation.

If ultralight forest zones exist, they can interact with a black hole under the right conditions. According to quantum theory, particles on a very small scale cannot be described by classical physics or even as individual objects. This scale, known as the Compton wavelength, is inversely proportional to the particle mass.

Since ultralight forest zones are particularly light, their wavelength is extremely large. For a certain mass range of bosons, their wavelength may be comparable to the size of a black hole. If this happens, super radiation is expected to develop rapidly. Ultralight bosons are then created from the vacuum around a black hole, in quantities large enough to drag the small particles together to the black hole and slow its rotation.

“If you jump up and down a carousel, you can steal energy from the carousel,” says Vitale. “This forest zone does the same to a black hole.”

Scientists believe that this slowdown of the boson could occur over several thousand years – relatively quickly on astrophysical time scales.

“If boson existed, we would expect old black holes of the appropriate mass not to have large turns, as the boson clouds would have extracted most of them,” says Ng. “This implies that the discovery of a large-hole black hole could preclude the existence of forest zones with certain masses.”

Turn up, turn down

Ng and Vitale applied this reasoning to measurements of black holes made by LIGO, the Laser Interferometer Gravitational-Wave Observatory, and its companion detector Virgo. The detectors ‘listen’ to gravity waves or echoes of distant disasters, such as the joining of black holes, known as binaries.

In their study, the team searched all 45 black hole binaries reported so far by LIGO and Virgo. The masses of these black holes – between 10 and 70 times the mass of the sun – indicate that if they had interacted with ultralight forest zones, the particles would have been between 1×10^-13 electron volts and 2×10^-11 electron volts in mass.

For each black hole, the team calculated the turn it would have had if the black hole were turned inside ultra-light bush zones within the corresponding mass range. From their analysis, two black holes stood out: GW190412 and GW190517. Just as there is a maximum velocity for physical objects – the velocity of light – there is an upper turn against which black holes can rotate. GW190517 turns close to the maximum. The researchers calculated that if there were ultralight forest zones, they would subtract the twist by a factor of two.

“If it existed, these things would have sucked up very angular momentum,” Vitale says. “They really are vampires.”

The researchers also took into account other possible scenarios for the generation of the large holes of the black holes, while the ultralight forest zone still exists. For example, a black hole could be spun through bosons, but then re-accelerate through interactions with the surrounding growth disk – a disk matter from which the black hole could absorb energy and momentum.

“If you do math, you find that it takes too long to turn a black hole up to the level we see here,” says Ng. “So, we can safely ignore this spin-up effect.”

In other words, the high holes of the black holes are unlikely to be due to an alternative scenario in which ultralight forest zones also exist. Given the masses and the large turn of both black holes, the researchers were able to rule out the existence of ultralight forest zones with masses between 1.3×10.^-13 electron volts and 2.7×10^-13 electron volts.

“We basically excluded some kind of forest zone in this mass range,” says Vitale. “This work also shows how gravity wave detections can contribute to the search for elementary particles.”

This story is published thanks to MIT News (web.mit.edu/newsoffice/), a popular website covering news about MIT research, innovation and teaching.