August 30, 2017
Experiment changes everything we know about black holes
A longstanding theory describing what happens to matter before it is consumed by a black hole is wrong, according to new experiments conducted at the planet’s most powerful X-ray scanner and detailed in research published earlier this month in the journal Physical Review Letters.
Black holes are regions of spacetime that have gravitational fields so powerful that they prevent anything from escaping, including light and radiation. This, as Newsweek explained, makes them rather difficult to study and forces scientists to rely on laboratory models to collect new data.During one such experiment, researchers at Sandia National Laboratories in Albuquerque, New Mexico created a plasma similar to the charged gas found around black holes at the facility’s Z Machine when they made a startling discovery that contradicts a longstanding but never proven assumption about the X-rays that surround a black hole.
As lead author Guillaume Loisel explained in a statement, emissions from black holes cannot be directly observed. Instead, “we see emission from surrounding matter just before it is consumed by the black hole,” he said. “This surrounding matter is forced into the shape of a disk, called an accretion disk.”
These accretion disks radiates in the X-ray spectrum, and as NASA astrophysicist Tim Kallman told Newsweek, they contain a lot of information. “They can have many shapes,” and they have “bumps and wiggles in different parts of the spectra,” he explained. By interpreting those bumps and wiggles, researchers can determine how much gas the accretion disk contains, how hot it is, how many different elements it contains and more.
Findings may invalidate two decades worth of scientific studies
One theory that has stood the test of time, despite never being proven, is known as the Resonant Auger Destruction assumption. This assumption addresses the lack of photons coming from the accretion disk by assuming that a black hole’s powerful gravity and radiation prevents energized iron electrons from returning to lower energy states by emitting photons.
For the last five years, Loisel and his colleagues have used the Z Machine to put this assumption to the test, according to Newsweek. The powerful X-ray scanner allowed them to recreate energy surrounding the black hole and apply said energy to matter. Essentially, Kallman said, they came closer than ever to recreating the conditions found around an actual black hole.
The Sandia researchers applied the X-ray energies found around black holes to tiny silicon pieces to see if they could witness the Auger effect. Even though they precisely recreated the conditions and temperatures found around a black hole, however, they did not find any evidence of photons.
“If Resonant Auger Destruction is a factor, it should have happened in our experiment because we had the same conditions, the same column density, the same temperature. Our results show that if the photons aren't there, the ions must be not there either,” Loisel told Newsweek. While he added that it is too soon to completely dismissing the Auger effect, he said that their findings “challenge models used to infer how fast black holes swallow matter from their companion star” and could invalidate “many scientific papers published over the last 20 years.”
Image credit: Randy Montoya/Sandia