Detecting Gravitational Waves
Scientists have announced the detection of four new gravitational waves, bringing the total to 11. First captured by the LIGO detectors in 2015, the new observations of ripples in the fabric of space-time are quickly adding up and helping researchers to better understand powerful and distant cosmic phenomena like black holes and neutron stars.
Scientists, using LIGO and the European-based Virgo gravitational wave detectors, have detected gravitational waves from a total of ten stellar-mass binary black hole mergers and one merger of neutron stars, which are the collapsed cores of giant stars.
A highlight of the new detections is a black hole merger from about 5 billion years ago that is the most massive and distant gravitational-wave source scientists have ever seen. This merger created a black hole 80 times larger than the Sun and released an amount of gravitational energy equivalent to the mass of five of our home star.
“Gravitational waves give us unprecedented insight into the population and properties of black holes. We now have a sharper picture of both how frequently stellar mass binary black holes merge and what their masses are. These measurements will further enable us to understand how the most massive stars of our Universe are born, live and die,” Northwestern University’s Chris Pankow, who led the analysis of black hole populations, said in a statement.
Thanks to these new detections, scientists have enough data to infer that all stellar-weight black holes weigh less than 45 times the mass of the sun. This work also shows how it’s possible that more binary black hole mergers occurred earlier in the universe, Pankow said to Discover.
While these detections reveal information about black holes, they also open doors to future research, Pankow explained. When gravitational waves were first physically detected in 2015, it was a major first. But with these 11 new detections, researchers have a wealth of new data and opportunities to explore gravitational waves and the events that create them.
In the past, our current understanding of black holes and these phenomena was supported by observations with X-rays and optical and radio waves. These methods have provided an overwhelming wealth of data and contributed immensely to astronomy and astrophysics. However, Pankow added, gravitational waves allow us to study and understand binary black holes in a way that can’t be done with other measures.
“That’s allowed for testing our understanding of what gravity really means,” Pankow said, adding that the researchers could also use these detections to better understand how stars evolve and die.
These findings are described in two papers available on arXiv, which houses electronic preprints that have not yet been peer reviewed. The papers can be found here and here.