The sounds captured are produced by the alteration of the time-space fabric during the merger of supermassive black holes.
Einstein’s theory of general relativity accurately predicts how gravitational waves affect radio signals emitted by the magnetic poles of extremely dense stars spinning on their axis, called pulsars, by stretching and compressing the fabric of space, altering time. in which the celestial bodies produce each pulse.
Now, thanks to the efforts of dozens of astronomers from around the world and more than 15 years of exhaustive research, scientists have managed to “hear” for the first time the perpetual ‘symphony’ of gravitational waves that undulate through our universe, reports the Observatory American Nanohertz for Gravitational Waves (NANOGrav).
As detailed by the institution, the existence and composition of gravitational waves has been theorized for nearly a century. In 2020, NANOGrav scientists identified a kind of ‘hum’ caused by ultra-low frequency waves by studying a set of pulsars. However, there was not enough evidence to determine the exact origin of the sounds captured.
A massive study
Finally, after observing 67 pulsars with massive radio telescopes in Europe, India, Australia and China, five research teams, in which more than 190 scientists participated, were able to independently detect similar signals, confirming that this ‘hum’ was caused by the gravitational waves by stretching and compressing the universe.
Unlike the high-frequency waves previously captured by the Laser Interferometer Gravitational-Wave Observatory (LIGO), gravitational-wave sound is produced by ultra-low-frequency waves, each of which could be up to tens of meters long. Light years.
In a series of articles published in The Astrophysical Journal Letters, astronomers explain that most of the gigantic gravitational waves captured are probably produced by pairs of supermassive black holes “spiraling into cataclysmic collisions throughout the cosmos.”
a cosmic orchestra
According to the researchers, when two galaxies merge, the black holes located in the center of each one orbit each other, forming a binary system. Over time, these will eventually merge, generating gravitational waves that propagate away from their home galaxy, like ripples on a pond, in the process.
“Gravitational wave signals from these giant binaries are expected to overlap, like voices in a crowd or instruments in an orchestra, producing a general background hum that imprints a unique pattern on the pulsar timing data.” , explain astronomers.
The analysis of gravitational waves, the scientists estimate, could shed new light on the origin and evolution of the universe, “providing information on the frequency of collision of galaxies and the reasons that drive black holes to merge”.
Currently, experts have only managed to capture the sound of gravitational waves as a whole, but they estimate that as research continues they will be able to study them individually.
“Our previous data told us we were hearing something, but we didn’t know what. Now we know it’s music from the gravitational universe. If we keep listening, we’ll probably be able to distinguish the notes of the instruments playing in this cosmic orchestra,” Scott said. Ransom, co-author of the research.
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