Astronomers discover “cosmic bass note” gravitational waves. According to scientists, the sound comes from the merging of supermassive black holes throughout the universe.
The rumbling “cosmic bass note” gravitational waves believed to be the result of the slow merger of supermassive black holes throughout the universe, astronomers have discovered.
As The Guardian writes, these observations are the first detections of low-frequency ripples in the fabric of space-time and promise to open a new window into the world of monstrous black holes that lie at the centers of galaxies.
These objects are in the millions, or even billions times the mass of the Sun and played a huge role in the formation of galaxies, but remain elusive because no light can escape from their clutches.
“This is huge news,” said Dr. Steven Taylor, chairman of the North American Nanohertz Gravitational Wave Observatory (Nanograv) Consortium that spearheaded the discovery, and an astrophysicist at Vanderbilt University in Nashville.
Dr. Michael Keith, lecturer at the Jodrell Bank Center for Astrophysics and member of the European team that provided the independent evidence for the signal, said: “Today's results mark the beginning of a new journey into the universe to unravel some of its unsolved mysteries. We are incredibly excited that after decades of work by hundreds of astronomers and physicists around the world, we are finally seeing signs of gravitational waves from a distant universe”.
Albert Einstein first predicted the existence of gravitational waves a century ago, and the breakthrough made in 2016 by the American Laser Interferometric Gravitational Wave Observatory (Ligo), was proof that space itself can stretch and shrink.
However, until now, scientists have been able to capture only short «bursts» of gravitational waves associated with mergers of black holes or neutron stars only slightly larger than the Sun, writes The Guardian.
Recent observations show that one full wave propagating at the speed of light passes the Earth in about 30 years . Scientists believe that this cosmic rumble is likely created by the entire collection of binary supermassive black holes over the past 8 billion years.
“We think that each pair contributes to a small wave that is added to the small wave of the other, and together this is what we can see right now – a kind of murmuring of the entire population,” says Professor Alberto Vecchio of the University of Birmingham and a member of the European Pulsar Synchronization System.
The discovery was made by carefully observing more than 100 pulsars – exotic stars that rotate hundreds of times per second, creating beams of radio waves that look like lighthouses. These pulses are so stable that you can pick up the slightest changes in time caused by the stretching and contraction of the fabric of space, notes The Guardian.
In 2020, with 12 years of data, nanogravitators began to notice hints of this gravitational hum and reached out to individual teams in Europe, India, China and Australia, each of which agreed to use their own data for independent verification.
Dr. Steven Taylor noted that the chances that the latest results are random are close to one in 10,000, making them strong evidence, although this falls short of the «one in a million» gold standard of physics; to claim evidence for a new phenomenon.
There is also an element of uncertainty about the source of gravitational waves. According to Taylor, the death spirals of supermassive black holes are seen as «the most plausible explanation,» but alternative possibilities remain under consideration, including a gravitational imprint left on the universe shortly after the big bang.
Professor Jocelyn Bell Burnell, who discovered pulsars as a graduate student, described the latest discovery as «an important and significant technical achievement.» “The effect is very small – one part per thousand million million, – so it's a precise job, she said. – They were very attentive and careful and did not scream prematurely.
Professor Andrew Pontzen, a cosmologist at University College London, admits: “It is not often that we get to look at the Universe through a completely new prism, but after 15 years of patient Nanograv's work seems to provide just that. It is extremely interesting to see the initial evidence for these waves, which will eventually tell us a huge amount about supermassive black holes, the mass of which is hundreds of millions of times the mass of the Sun”.
The results are outlined in a series of articles published on Thursday in Astrophysical Journal Letters.