(ORDO NEWS) — Scientists from the United States and Canada reported that they were able to detect signs of constant gravitational radiation that travels through the Universe and distorts the fabric of space-time. The research results are published in The Astrophysical Journal Letters.
In 2017, scientists conducting an experiment called the Laser Interferometric Gravitational Wave Observatory (LIGO) received the Nobel Prize in Physics for the first-ever direct detection of gravitational waves from the merger of two black holes located about 1.3 billion light years from Earth. The waves generated by this collision violated the gravitational-wave background of the Universe and reached the Earth.
In addition to such one-time strong disturbances, which astrophysicists have already learned to detect, there is the so-called background of gravitational waves – a constant flow of gravitational radiation, which, according to the theory, is constantly washing the Earth.
It is this background radiation that scientists from the North American Nanohertz Gravitational Wave Observatory (NANOGrav) project were trying to detect. For 13 years, they studied the light emanating from dozens of pulsars scattered throughout our galaxy, using it as a huge space observatory, to find hints of a unique gravitational ripple in the universe.
“We found a strong signal in our dataset. We cannot yet say that these are background gravitational waves, but our target is getting closer,” the lead author of the new article, astrophysicist Joseph Simon, quoted in a press release from the University of Colorado Boulder. Simon).
“These early hints of a gravitational wave background suggest that supermassive black holes are indeed merging, and that we are wobbling in a sea of gravitational waves from merging supermassive black holes in galaxies across the universe,” says study author Julie Comerford. Comerford, Associate Professor in the Department of Astrophysics and Planetology, University of Colorado.
NANOGrav is merged with two more projects from Europe and Australia into a single research network called the International Pulsar Timing Array, which searches for gravitational waves on an ongoing basis.
According to the authors, no other observatory is able to detect background gravitational waves, because they are focused on searching for one-time events lasting several seconds.
“We’re looking for waves that last for years or decades,” Simon notes. “According to the theory, mergers of galaxies and other cosmological events cause a constant burst of huge gravitational waves. It takes years or even longer for one such wave to pass by the Earth. other existing experiments cannot detect them directly. ”
To fix the background gravitational noise, NANOGrav scientists used ground-based telescopes to observe pulsars – cosmic sources of blinking pulses, bursts of radio emission, the frequency of which remains unchanged. Pulsars can be compared to galactic lighthouses that are constantly in the same place.
The transmitted gravitational waves alter the stable pattern of light emanating from pulsars, increasing or contracting the relative distances that these rays travel through space. In other words, scientists can theoretically detect the background of gravitational waves by tracking correlated changes in the time of arrival of pulsar radiation on Earth.
The scientists’ task was to observe as long as possible and as many pulsars as possible. To date, data has been collected for several years on 45 pulsars.
“The ability to detect the background of gravitational waves is a huge, but only the first step,” Simon emphasizes. “Step two is to determine what causes these waves and find out what they can tell us about the universe.”
An analysis of the observations showed that the light emanating from the pulsars is influenced by some general background process. Researchers are not yet sure what exactly is causing the signal drift.
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