“This is the first-ever evidence for the gravitational wave background. “It’s like a choir, with all these supermassive black hole pairs chiming in at different frequencies,” said study coauthor and NANOGrav scientist Chiara Mingarelli, assistant professor of physics at Yale University, in a statement.
They were likely caused by collisions of supermassive black holes and carry about a million times as much energy as the singular events detected in recent years that resulted from black hole or neutron star mergers. The newly detected gravitational waves are the most powerful ever measured. Their findings appear in a study published Wednesday in The Astrophysical Journal Letters. They tracked the radio waves from more than 60 pulsars for 15 years using three large radio telescopes: the Arecibo Observatory in Puerto Rico ( which is no longer operational), the Green Bank Telescope in West Virginia and the Very Large Array in New Mexico. More than 190 scientists set out to discover the frequencies of gravitational waves as part of the North American Nanohertz Observatory for Gravitational Waves collaboration, also known as NANOGrav. This means some of the pulses reach Earth a fraction of a second earlier or later than expected. Einstein theorized that gravitational waves would stretch and compress space as they moved across the universe, affecting how radio waves travel. When gravitational waves pass between Earth and a pulsar, the radio wave timing of the pulsar is disrupted. Scientists spot a planet that shouldn’t exist Pulsars can spin hundreds of times each second, and the stable precision of the pulses makes them as reliable as cosmic clocks. Pulsars are like stellar lighthouses, rapidly spinning and releasing beams of radio waves that seem to “pulse” when viewed through Earth-based telescopes. Gravitational waves, initially predicted by Albert Einstein in 1916, are ripples in space-time that were first detected in 2015.Īstronomers found the waves by tracking pulsars, or the dense remnants of cores belonging to massive stars after they explode in a supernova, across the Milky Way. The discovery could help scientists better understand cosmic phenomena like supermassive black holes and how often galaxies merge. Their observations reveal that the waves - including some that slowly undulate as they pass through our Milky Way galaxy - occur at different frequencies and oscillate for decades. Astronomers have been able to “hear” the celestial hum of powerful gravitational waves, created by collisions between black holes, echoing across the universe for the first time.
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