Unknown Type Of Gravitational Waves

in STEMGeeks2 months ago

It sounds innocent enough. The Australian detector of gravitational waves Bulk Acoustic Wave detected two events we had never seen before. But it could be caused by cool stuff like primordial black holes or even dark matter.


Image by Alexander Antropov from Pixabay

Since 2015 we know for sure that gravitational waves do exist. They were first observed by gravitational astronomers that search the Universe in a completely new way. So far, they hunted gravitational waves at the LIGO observatory that is capable of detecting gravitational waves at frequencies between 7 kHz and 30 Hz. These correspond to universal catastrophes such as black holes or neutron star collisions.

That’s certainly awesome. But at the same time, there definitely are different types of gravitational waves outside of these limits. These are the ones that are being targeted by new gravitational experiments such as the Bulk Acoustic Wave resonator (BAW). Recently, the team from the ARC Center of Excellence for Dark Matter Particle Physics and the University of Western Australia got the first batch of data out of it that comes with the events that could be an unknown type of gravitational waves.

The BAW experiment uses a silicone crystal disk through which acoustic waves pass through. This makes it vibrate at very high frequencies creating electrical current that can be observed by two conductive plates that push on the disk from both sides. This creates a signal that go into the device known as SQUID (Superconductive QUantum Interference Device) that amplifies it for the detector itself.

The whole system is placed in several anti-radiation shields that protect BAW from surrounding electromagnetic radiation. At the same time, it is frozen almost to absolute zero to get rid of thermal noise. This construction allows BAW to detect gravitational waves in the MHz frequency range.

The BAW experiment has been running for a total of 153 days of the year 2019. During this time it detected two special and so far unseen events. First on the 12th of May and then on the 27th of November. Both of these events could be caused by gravitational waves around 5 MHz.

At this time we aren’t sure what these signals are. But there are some fascinating options at play. One of the possibilities are primordial black holes that could have been existing since the very first moments of existence after the Big Bang. But we still aren’t sure whether they exist or not. Another – possibly even cooler option – is that these signals come from clouds of dark matter particles that passed through the BAW detector.

As the scientists acknowledge, there are also much more simple explanations for the detected signals. It could be interference coming from electrically charged particles, the result of mechanical stress, or even random phenomena at the atomic level. Thus, the next goal of the gravitational astronomers is to find out what exactly happened. And no matter what did happen, we can be sure scientists and the world will have a lot more fun with gravitational astronomy.


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