Supermassive black holes emit gravitational waves that
Ripple the fabric of space-time. / NASA/JPL-Caltech
Astronomers from different parts of the world have heard for the first time the hum of the waves flowing in the Milky Way. This discovery could help understand how the universe, galaxies and black holes were formed.
Gravitational waves were predicted by Albert Einstein in 1915. Throughout history, they have been theorized about and it was not until 2015 that they were experimentally detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO). Now, the investigations have confirmed their presence.
After 15 years of data collection, joint efforts and fine-tuning the listening, a group of scientists from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), published the finding in ‘The Astrophysical Journal Letters’.
Gravitational waves are disturbances in the fabric of space-time, and since ten years ago, in 2020, NANOGrav scientists detected signs of an additional widespread ‘hum’. Three years later, they published the discovery after having accumulated enough concrete evidence on the background of gravitational waves.
“The NANOGrav 15-year data set contains observations of 68 pulsars obtained between July 2004 and August 2020 with the Arecibo Observatory (Arecibo), the Green Bank Telescope (GBT) and the Very Large Array (VLA)”, mentions the publication.
In this research that could reveal secrets of the Big Bang, a galaxy-sized antenna of millisecond pulsars in the Milky Way was used, a kind of virtual ‘laboratory’.
“It’s like a choir, with all these pairs of supermassive black holes resonating at different frequencies. This is the first evidence we have of the background of gravitational waves. We have opened a new observation window of the Universe,” said Chiara Mingarelli, researcher at NANOGrav.
Digital simulation of a supermassive black hole / NASA, ESA, and D. Coe, J. Anderson, and R. van der Marel (STScI)
Stephen Taylor, gravitational wave astrophysicist at Vanderbilt University in Tennessee and co-director of the research, said that the signal detected is evidence consistent with theoretical expectations of gravitational waves emerging from pairs of supermassive black holes, weighing as much as billions of suns.
These waves, which shrink and stretch the fabric of space-time as they travel at the speed of light. They are the most powerful measured so far, and could also be generated by something else, such as the echo of cosmic strings.
“What comes next is everything. This is just the beginning,” said researcher Chiara Mingarelli.
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