In the video below, a visualization of a millisecond pulsar, surrounded by an accretion disk of gas and dust. (Video credit: NASA)
Currently, gravitational wave astronomy is in its infancy, using revolutionary detectors like the Laser Interferometer Gravitational-Wave Observatory (LIGO).
This detector — located in Washington state and Louisiana — is able to measure tiny changes on Earth caused by interactions with gravitational waves. As gravitational waves interact with our planet, the result is slight changes in the timing of regular signals from pulsars.
“This signal is incredibly enticing. It could be that our orchestra is tuning up, hinting that we’re about to hear the grand symphony of waves from supermassive black holes that we expect pervades the Universe… If this signal is indeed gravitational waves, future study will offer unique insights into how the biggest black holes and galaxies in our universe form and evolve,” Sarah Burke-Spolaor, professor at the Physics and Astronomy Department at WVU, states.
The NANOGrav team examines timing of pulsars around the Cosmos — a pulsar timing array — searching for tiny variations that signal the presence of gravitational waves.
“Einstein had looked at the numbers and dimensions that went into his equations for gravitational waves and said, essentially, ‘This is so tiny that it will never have any influence on anything, and nobody can measure it.’ And when you think about the times and the technology in 1916, he was probably right.” — Rainer Weiss
Millisecond pulsars rotate hundreds of times per second. However, not all pulsars are suitable for the study of these elusive ripples in spacetime. Of the 47 millisecond pulsars considered by the team, 45 had at least three years of timing data, allowing researchers a large enough of a dataset to include in the study.
Individual pulsars did not contain enough information to reach meaningful conclusions, but the 45 pulsars together provided a pool of data large enough to show signs of gravitational waves. However, confirmation of this finding will require more data from additional pulsars recorded over a longer period of time. The recent loss of the Arecibo Radio Telescope will require NANOGrav researchers to gather data from additional observatories around the globe.
The team was able to eliminate other possible causes of the timing variations seen by astronomers, including contributions from objects in our solar system or errors in data collection. The team is currently developing computer simulations, designed to test whether such signals come from any source other than elusive gravitational waves.
