How does a galaxy-sized observatory sound?
Scientists are going to turn the Milky Way into a giant galaxy-sized observatory to observe gravitational waves too large for conventional ground-based instruments.
Cosmic catastrophes, such as the merging of black holes or neutron stars, can create gravitational waves – “folds in space-time” – and in 2016, the LIGO and Virgo observatories recorded such an event for the first time. Since then, scientists have been able to observe them more and more often.
Theoretically, the Universe is penetrated by predominantly “calm” waves, imperceptibly filling it with a weak gravitational noise. It is impossible to observe them on LIGO or Virgo: one such wave can pass through the Earth for years without allowing us to notice it.
Participants in the joint American-Canadian project NANOGrav propose to use a different approach for this – the timing of pulsars. They talk about this research in-depth in an article published in The Astrophysical Journal Letters.
The essence of the new project is the creation “galaxy-sized observatory” that will include a global international network of telescopes called the International Pulsar Timing Array (IPTA), which will track the light of distant pulsars of the Milky Way.
Such objects are distant, rapidly rotating neutron stars that emit powerful, narrowly directed fluxes of radiation. When rotating, these rays fall into the observer’s field of view at strictly equal intervals of time, causing them to pulsate with high periodicity.
But the passage of a gravitational wave should slightly, by several nanoseconds, change the recording time of these flares. Thus, by accurately tracking the timing of distant pulsars, it is theoretically possible to detect the gravitational-wave background of the Galaxy.
This is confirmed by the preliminary results of the NANOGrav project. As part of the experiment, scientists have been tracking 45 pulsars over several years – and have already found signs of slight changes in their frequency.
Nevertheless, this is not enough for final conclusions. Therefore, astronomers have announced plans to create IPTA – a network of instruments that will record such deviations for a large number of pulsars at the same time and without interruptions. Simply said, a galaxy-sized observatory far more advanced than the technology we currently have on the ground.
Overall, this approach will undoubtedly be huge for the future of space exploration but I have to say that this will only be the beginning. The ability to detect such gravitational waves would be a massive success but to be fair, this will only be a small part of the whole process.
Detecting them is one thing but finding their actual sources will be the most crucial part of the entire research. We can only wonder what these waves and their sources could tell us about the Universe we live in.
To give you a better idea of the significance of this research and the discoveries that we will surely see in the upcoming years, I will give you an example with the case of the experiment that detected the first gravitational waves of this kind in 2016.
A year later, the team of scientists behind the discovery won the Noble Prize in Physics. This should be a clear example of the importance of a galaxy-sized observatory.
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• Arzoumanian, Z. (2020, December 24). The NANOGrav 12.5 yr Data Set: Search for an Isotropic Stochastic Gravitational-wave Background.
• ‘Galaxy-sized’ observatory sees potential hints of gravitational waves. (2021, January 11).
• ‘Galaxy-sized’ observatory sees potential hints of gravitational waves. (2021, January 12).
• ROBITZSKI, D. (2021, January 12). New technique uses entire Milky Way as a giant observatory.