Scientists have detected gravitational waves coming from the collision of two neutron stars, and, for the first time, captured their image.
Some 130 million years ago, in a nearby galaxy, two neutron stars collided. The cataclysmic crash produced gravitational waves, ripples in the fabric of spacetime that traveled across the universe.
On August 17, 2017, along with hundreds of other collaborators around the globe, Marcelle Soares-Santos, assistant professor of physics at Brandeis University, finally got to see them.
“This is a whole new window into the universe…”
The finding remained under wraps until today, when the announcement came from the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo, the umbrella organizations overseeing the worldwide search for gravitational waves. Researchers are heralding the discovery as the dawn of a new era of scientific discovery, when analyzing gravitational waves will offer answers to some of the biggest mysteries in cosmology.
In the short term, we will gain new insights into neutron stars, which occur when giant stars 10 to 30 times as big as the sun collapse into objects about the size of the greater Boston metropolitan area. But over a longer period, gravitational waves may explain the universe’s continued expansion and the composition of dark energy, an elusive, mysterious substance that makes up roughly 70 percent of the universe.
“This is a whole new window into the universe,” Soares-Santos says. “This is beyond my wildest dreams.”
Soares-Santos previously worked for more than a decade at the Fermi National Accelerator Laboratory, part of the US Department of Energy. Every winter, she has journeyed to a mountaintop in northern Chile to peer at the stars through the Cerro Tololo Inter-American Observatory’s telescope, one of the most powerful in the world.
A year ago, LIGO scientists also reported they’d discovered gravitational waves, but those were from the merger of two black holes, not neutron stars. The signals for black hole gravitational waves usually last less than a second while those from neutron stars persist for as long as a minute, providing reams more data.
In addition, the black hole research involved recording the vibrations gravitational waves cause as they distort spacetime. (They sound like a series of small thumps.) But this time around, in addition to capturing these vibrations, Soares-Santos and her colleagues in Chile captured the waves’ optical signal. An image yields far more precise information than the sound recordings.
“The optical signal lets us do the equivalent of actually going there and looking at the neutron star merger,” Soares-Santos says.