A collaboration named NANOGrav recently made a new discovery that could help scientists learn about what dark matter and dark energy are made of. Using the largest radio telescopes in the United States, NANOGrav has been monitoring nearly 80 pulsars for signs gravitational waves.
What is NANOGRAV?
NANOGrav, short for North American Nanohertz Observatory for Gravitational Waves, is a group of scientists and astronomers looking for signs of gravitational waves. By watching the rotations of dead stars, they are able to detect these very minute fluctuations in space.
What is a gravitational wave?
A gravitational wave is most commonly caused by the event of two black holes merging together. As these black holes circle each other, they create spiral-shaped waves that spread out across the universe. As these cross the universe, they stretch and squeeze anything they pass by. This stretching and squeezing is the movement we can detect.
How do we detect gravitational waves before?
In 1999, construction on the LIGO project finished. LIGO was made of two 2.5-mile-long perpendicular tunnels. Lasers are bounced off mirrors at the end of each tunnel back to their starting point. Here, the lasers are measured. When a gravitational wave passes by, it distorts the alignment of these lasers. It has run three times.
The first time LIGO ran, O1, detected three black hole mergers, between the dates of 12 September 2015 and 19 January 2016. The second run, O2, detected seven black hole mergers and one neutron star merger between dates 30 November 2016 and 25 August 2017. The third run, O3, detected 79 mergers, one of them being the first detected merger of a black hole and a neutron star. The next run, O4, began in 24 May 2023.
How does NANOGRAV detectors work?
Using pulsars, NANOGrav has done just that. Pulsars are the dead cores of stars created by big supernovae. These highly magnetic cores are about the size of a city and are capable of spinning hundreds of times a second. Lots of pulsars also have jets streaming out from the magnetic poles.
What will NANOGrav discover?
Despite how many mergers LIGO has detected, it can only detect the higher frequency gravitational waves. In order to detect the lower frequency waves, a detector would need to be much larger than 2.5 miles. NANOGrav looks for radio jets made by pulsars pointing toward Earth. By monitoring the time between the radio flashes from pulsars, NANOGrav has been able to detect the deformations of space caused by gravitational waves.
By the time a pulsar’s radio jets reach Earth they are pretty faint. Because of this, NANOGrav uses some of the largest radio telescopes in the United States: The Very Large Telescope, the Green Bank Telescope, and the Arecibo Telescope. These telescopes keep track of nearly 80 different pulsars making a detector the size of the Milky Way itself!
What does this new system mean for science?
Because this pulsar detection system is so large, scientists are able to study the effects of multiple gravitational waves on different nebulae and star systems throughout the Milky Way. It might also help scientists discover what dark matter and dark energy are made of, since these only interact with our universe using gravity. The potential discoveries are endless.
a a a a a a a a a a a a a