Hidden gravitational wave discloses black holes

A gravitational wave echoed across Earth like the clear tone of a bell in 2017. It pushed and crushed every person, ant and scientific instrument on the planet as it passed through space.

Hidden gravitational wave discloses black holesNow, researchers have gone back and studied that wave, and hidden data found in it helping in verify a decades-old astrophysics concept.

For the first time, astronomers had a tool that can detect and record it as it passed, known as the Laser Interferometer Gravitational-Wave Observatory (LIGO). They found first wave and two black holes crashing together far away in space as the outcome of result.

And now, a group of astrophysicists observed the recording and discovered something others believed would take years to reveal precise confirmation of the “no-hair theorem.” This important aspect of black hole theory times back at least to the 1970s, a theorem that Stephen Hawking well questioned.

Black holes only vary from each other in three ways: rate of spin, mass and electric charge. And in the real world, black holes probably don’t differ much in electrical charge, so they truly vary in terms of mass and spin. Physicists call these bald objects “Kerr black holes.”

At the time, that wave used a lot of information. The black hole behaved as expected. There were no clear signs that it lacked an event horizon (the region beyond which no light can escape) and it didn’t theatrically deviate from the no-hair theorem.

Matt Giesler, a physicist at the California Institute of Technology, pointed out that there was a short-term period right after the collision where the ringdown was intense enough that LIGO recorded more detail than usual. During those moments, the wave was loud enough that LIGO picked up an overtone a second wave at a different frequency, very much similar to the faint secondary notes that are carried in the sound of a struck bell.

Isi and his team revealed that the overtone pretty much matched that prediction. However, the recording of the overtone wasn’t actually clear, so it’s still possible that the tone was slightly different by about 10% from what theorem would predict.

To get beyond that level of accuracy, he stated, you’d require to draw out a clearer overtone from the waveform of a black hole accident, or develop more delicate instrument than LIGO.

However, Isi said, it’s always possible that black holes aren’t completely bald, may have some major peach fuzz that’s simple too soft and short for our instruments to pick up.