What does the discovery of a new black hole look like from Earth? According to astrophysicist and Forbes 30 Under 30 alumnus Karan Jani, it looks like a few wiggles that last for about 0.1 seconds. Jani is on a team that published a new paper Wednesday revealing that these unassuming “wiggles” are gravitational waves caused by an elusive, intermediate-mass type of black hole. It’s the first time a new type of black hole of this size has been detected solely using gravitational waves.
“Most astrophysicists did not believe this type of black hole existed,” Jani says. “This is the first confirmed evidence that black holes can exist in this medium-mass range.”
The idea of using gravitational waves to detect black holes is both very young and very old. In 1916, Albert Einstein predicted the existence of gravitational waves: invisible ripples in space-time that propagate through the universe after an energetic event. But it took almost 100 years for scientists to confirm the existence of these waves, which were found by the Laser Interferometer Gravitational-wave Observatory (LIGO) group in 2015 (this discovery won the 2017 Nobel Prize in Physics). Since then, scientists have been using gravitational waves to investigate black holes across the universe.
There are several classes of black holes, the most common of which are supermassive black holes, which are millions of times as massive as our sun, and stellar black holes, which are 10 to 24 times the mass of our sun. As the name implies, intermediate-mass black holes are the Goldilocks of the universe; this new black hole weighs in at about 142 times the mass of the sun. The researchers think that this black hole was created by two smaller black holes that collided and merged eons ago. The new black hole, which has not yet been named, is about 17 billion light years away.
Jani, who is 32 years old and the co-author of more than 100 scientific publications, has long believed in the existence of the elusive intermediate-mass black hole. But the lack of evidence has made some other scientists skeptical, he says. “It was clear that this had to be a rare process, because if it were too common we would have seen other hints.”
In May 2019, two days after his birthday, Jani and his colleagues found the first wiggles that indicated the existence of this medium-sized black hole. “You could see just a few wiggles in the detector,” he says, “but within those wiggles lies everything we need to understand about black holes.” A multinational group of scientists has spent the year since verifying the finding and trying to understand what this new discovery means. “This is a big collaboration with a thousand scientists, a hundred institutions,” Jani says.
The discovery of an intermediate-mass black hole also raises many questions: How exactly was it formed? And how often do this size of black holes occur?
Jain’s next project is going to try to answer some of these questions by taking gravitational wave detection to the cosmos. He’s currently working on the Laser Interferometer Space Antenna (LISA), a project led by NASA and the European Space Agency that aims to build a gravitational wave observatory in outer space. The project, planned for 2034, will involve the launch of three spacecraft that will follow Earth’s orbit in a triangle formation, and use the relative silence of outer space to detect even more gravitational waves.
In the meantime, Jain continues to be amazed by the mysteries of the world beyond our planet. “This discovery was a reminder of how humble we have to be in front of the universe,” he says. “No matter how much we try to rationalize it, it always has a way to fascinate us.”