New Astrophysics Model Shows How a Supermassive Black Hole Eats Stars
In 2016, an animated Neil deGrasse Tyson ate a bowl of pasta on the Cartoon Network’s Regular Show to illustrate what it looks like when a “spaghettified” star gets sucked into a supermassive black hole. It was not the most accurate depiction of what astrophysicists call a “tidal disruption event,” but it did capture the powerful, slurping horror of the black hole’s event horizon. A far more scientific description of the same event is described in an Astrophysical Journal Letters article, published Wednesday.
The scientists who wrote the paper, led by University of Copenhagen astrophysicist Lixin Dai, Ph.D., reveal what actually happens to a star as it gets devoured by a black hole using a new, “unified” computer model. Astrophysicists have plenty of data about black holes — observations about X-ray emissions, visible light, gas, and UV rays — but the new model is one of the first to put all of those pieces together in a consistent way. Having a model like this is important because, as the authors point out, our snapshots of black holes are not always taken from the ideal angle — and there’s often more to those pictures than meets the eye. Now they can feed data into the model to uncover the details they can’t see.
As the model came together, it became very clear that supermassive black holes eat stars in a fairly predictable way. Through the model-generated diagram below, the authors of the paper explain what actually happens to the star as it approaches the black hole’s “event horizon,” which is essentially the edge of its gaping maw. The black hole is shown as a black hole.
First, the star begins disintegrating into a disk of debris called an “accretion disk” because the black hole’s gravitational field is so strong. The black hole eats up all the debris (the slim part of the orange-yellow gradient), and once that debris enters the black hole, it gets “spaghettified” — stretched vertically and compressed horizontally into noodle-y streams of atoms — and slurped up.
However, the black hole can become “overfed,” so some stellar debris hangs out around the mouth of the black hole, not unlike crumbs left over on a facial beard (the fat part of the disk). These crumbs are important, because they’re what we can see from Earth: The process of getting sucked up is a hot one, and as the debris heats up, it emits light and radiation (shown as a double-headed arrow in the image), which we can detect from Earth. Now, even though our snapshots of black holes might show us only some of that crumb radiation, we can use the model to understand how big the mess actually is.
As theoretical astrophysicist Katie Mack, Ph.D. recently explained on the Inverse podcast I Need My Space, black holes are indeed messy eaters. “[Stars] do fall into black holes sometimes and get ripped apart,” she said. “And we can see like bursts of radiation from the vicinity of black holes sometimes from stars being disrupted as they’re falling into black holes. It’s just really neat.”
In a statement released Wednesday, the University of Copenhagen’s Enrico Ramirez-Ruiz, Ph.D., a co-author on the new study, explained why it’s so important that the model can help us visualize a black hole from all sides. “It is like there is a veil that covers part of a beast,” he said. “From some angles we see an exposed beast, but from other angles we see a covered beast. The beast is the same, but our perceptions are different.”
These beasts, as we’ve long known, are hungry ones. And thanks to the new model, we have a better idea of what black holes look like while they’re eating, making them far easier to hunt.