An international group of researchers, including Montana State University astrophysicist Neil Cornish, will work together over the next four years to study the physics of strong gravity using gravitational wave data. The project is funded by an $8 million grant from the Simons Foundation.
The Simons Collaboration on Black Holes and Strong Gravity brings together 12 scientists from different fields and institutions. Neil Cornish, who leads MSU’s eXtreme Gravity Institute, will head the observational science aspect of the research. Nicolas Yunes, a former MSU colleague now at the University of Illinois Urbana-Champaign, will direct the overall collaboration.
“This kind of big collaboration of experts in this area is something we’ve been working on developing for many years,” said Cornish, who serves on the executive committee for the collaboration.
Gravitational waves are disturbances in space-time caused by intense cosmic events like black hole mergers or neutron star collisions. Predicted by Einstein in 1916 as part of his general theory of relativity, these waves were first detected directly in 2015 by LIGO (Laser Interferometer Gravitational-wave Observatory). Since then, around 300 gravitational wave events have been observed. With technological improvements expected soon, that number could increase to thousands within five years as more observations are made using facilities such as Advanced LIGO in Louisiana and Washington state, Virgo in Italy, and KAGRA in Japan.
“That will go up into the thousands of events,” said Cornish. “We’re exploring a dramatically larger volume of the universe than we were 10 years ago. Now we get events on a weekly basis, but it will become a daily basis.”
The collaboration aims to link Einstein’s predictions about strong gravity with actual gravitational wave data collected from places where gravity plays a dominant role—such as black holes—since some predictions remain untested.
“One of the themes is to look for any departures from the predictions of Einstein’s theory,” Cornish said. “We have members of the collaboration who specialize in doing those kinds of calculations, in addition to working on the observations.”
Yunes explained that building an international network now is important because growing amounts of complex data require careful analysis and interpretation by specialists from various disciplines.
“The data isn’t just nice and pure, because instruments have little pops and crackles, a little bit like an old record player. You don’t want to interpret a crackle or pop to say Einstein’s theory was wrong, so you have to be careful,” Cornish said. “Those of us connected with the observations have a theoretical background, so we understand the physics behind these strong-gravity effects and come up with ways to extract that information from the data.”
Other team members bring expertise in areas such as perturbation theory, mathematical relativity, numerical relativity, observational gravity methods, Bayesian data analysis and machine learning. Together they plan to develop computer models and analytical techniques to better understand what can be learned from new gravitational wave signals.
“Through our collaboration, we will work to understand gravity in the most dynamic and violent astrophysical environments when black holes collide and gravity is dynamical and strongly nonlinear,” Yunes said. “Understanding gravity in this extreme environment can reveal a lot about nature.”
The funding will support graduate students and postdoctoral researchers for each principal investigator—including Cornish—and allow for workshops as research continues.
Cornish noted that after nearly ten years since detecting gravitational waves directly for the first time scientists still find no clear evidence contradicting Einstein’s theories: “As we keep on probing more and more, we don’t necessarily expect any differences we find to be huge. We’re potentially looking for something quite subtle,” he said.
The Simons Foundation was established in 1994 in New York City with goals that include advancing mathematics and basic sciences through research grants.
