Marcel Soares Santos, a University of Michigan astrophysicist who was not involved in the work, acknowledged that although this was early evidence, the results were attractive. “This is something that the community has long expected,” she said, adding that independent measurements from other pulsar timing collaborations bolstered the findings.
However, Dr. Soares-Santos said, it is too early to know what effect this gravitational wave background might have on future research. If the signal is indeed from the slow, internal spiraling of supermassive black holes, as several NANOGrav collaborators believe, it will increase what scientists understand about the way early galaxies merged, forming larger systems of stars and dust that eventually settled into the complex. structures observed today.
But if the ripples originated with the Big Bang, they might instead provide insight into the expansion of the universe or the nature of dark matter — the invisible glue that scientists think holds the universe together — and perhaps even reveal new particles or forces that once existed. (Experts note that gravitational wave background can also originate from multiple sources, in which case the challenge would be to separate how much is coming from where.)
The NANOGrav team is already analyzing all the data from gravitational wave collaborations around the world, with 25 years’ worth of measurements from 115 pulsars. These results will be revealed within a year or so, Dr. Siemens said, adding that he expects them to exceed the 5 sigma detection level.
But a few more years may be needed to confirm the source of the gravitational wave background. Researchers have already begun using their data to compile maps of the universe and search for nearby regions intense for gravitational-wave signals that point to a single supermassive black hole binary. That’s where the fun begins, said Dr. Mingarelli, who is looking to analyze those maps and look for more exotic phenomena, such as galactic jets, cosmic strings or wormholes.
“This could lead to something really new,” said Dr. Soares Santos, comparing it to the discovery of the cosmic microwave background in the 1960s, which has since transformed physicists’ knowledge of the early universe. “We don’t know yet what effect it will have, but it will definitely be a new chapter in the gravitational-wave book. And it looks like we’re watching the writing of that book.”
Denise Overby Contribute to the preparation of reports.