When a star wanders too close to a black hole, it doesn't end well. The black hole's gravity stretches the star apart like taffy, then consumes what's left. These violent events, called tidal disruption events or TDEs, flash brilliantly across the universe — and a new telescope is about to spot more of them than ever before.
NASA's Nancy Grace Roman Space Telescope is set to launch on August 30, 2026. Unlike most telescopes that just glance around, Roman will stare at the same patches of sky over and over again. This patience will let it catch these cosmic light shows happening billions of years ago.
"The Roman Space Telescope is going to be transformative for transient science," said Mitchell Karmen, a graduate student at Johns Hopkins University and the study's lead author.
Here's why that matters: supermassive black holes sit at the centers of most galaxies, including our own Milky Way. Scientists know they exist, but they don't fully understand how they grow so enormous — some weigh billions of times more than our Sun. To figure it out, researchers need to study these giants when they were younger.
Roman can detect black holes from up to 11 billion years ago, when the universe was less than a quarter of its current age. But there's a catch: smaller black holes are harder to spot because they're dimmer. That's where tidal disruption events become useful.
When black holes weighing between 100,000 and 100 million suns tear apart a star, they flare up and can briefly outshine their entire galaxy. Heavier black holes — those over 1 billion solar masses — simply swallow stars whole, making them nearly invisible. TDEs are essentially a spotlight on the "lighter" supermassive black holes that scientists otherwise struggle to observe.
Roman's survey will cover 18 square degrees of sky, an area equal to about 90 full moons. By watching these regions repeatedly, astronomers expect to find up to 100 TDEs per year — fewer than some ground-based telescopes, but those events will be much more distant and ancient.
"Just by counting the number of TDEs as a function of redshift, you can put meaningful constraints on the population of million-solar-mass black holes," said co-author Suvi Gezari, an astronomy professor at the University of Maryland.
The research, published in The Astrophysical Journal, predicts that TDE rates will increase as Roman looks further back in time, peaking around "cosmic noon" — roughly 11 to 12 billion years ago, when star formation across the universe was at its height — before declining again.
In other words, Roman won't just find black holes. It'll help scientists piece together the origin story of these cosmic giants.