LIGO’s range centers on stellar remnant black holes and other celestial objects of similar mass. If we've already detected gravitational waves, why is NANOGrav necessary? It's because the collaboration is looking for different frequencies of gravitational waves. That first direct detection was announced on February 11, 2016, spawned headlines worldwide, snagged the 2017 Nobel Prize in Physics, and officially launched a new era of so-called "multi-messenger" astronomy. (A third detector in Italy, Advanced VIRGO, came online in 2016.) On September 14, 2015, at 5:51 am ET, both detectors picked up signals within milliseconds of each other for the very first time-direct evidence for two black holes spiraling inward toward each other and merging in a massive collision event that sent powerful shockwaves across spacetime. LIGO has detectors in Hanford, Washington, and in Livingston, Louisiana. That said, "In our statistical analyses, there's a less than 1-in-1,000 chance of nature giving our results without gravitational waves being present," NANOGrav chair Stephen Taylor of Vanderbilt University said during a press briefing.Īs previously reported, LIGO detects gravitational waves via laser interferometry, using high-powered lasers to measure tiny changes in the distance between two objects positioned kilometers apart. The collaboration stopped short of claiming outright detection, opting to describe their results instead as strong evidence of the expected gravitational wave background. The results and related analyses are described in several new papers published in the The Astrophysical Journal Letters.
Now the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has announced the first evidence of this gravitational wave background. But an expected corresponding low-frequency gravitational wave background-a kind of "hum" comprised of a chorus of gravitational waves, most likely emanating from binary pairs of supermassive black holes-has proven more elusive.
Gravitational waves are ripples in the fabric of spacetime predicted by Albert Einstein's general theory of relativity, first detected in 2015. Aurore Simonnet for the NANOGrav Collaboration reader comments 46 with
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