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Seeing the light in black holes: Sandia researchers disprove a theory

Copyright © 2017 Albuquerque Journal

There’s hardly anything denser than a black hole, both as a celestial object and subject matter.

It’s hard to study things we can’t directly observe that are millions of light-years away.

But researchers at Sandia National Laboratories in Albuquerque have used the world’s most powerful X-rays to synthesize the conditions directly around one.bright spot

In doing so, they’ve disproved a widely held assumption about the mysterious phenomenon.

Using the “Z Machine,” researchers mimicked conditions of accretion disks – the swirling, superheated masses of gas and debris about to be sucked into the depths of a black hole.

Sandia researcher Guillaume Loisel stands with the Z Machine, which he and fellow researchers used to re-create the conditions near black holes. Loisel is the lead author of a paper on the results. (Courtesy of Randy Montoya)

“We, for the first time on Earth, created an experiment that can study these objects,” said Sandia researcher Guillaume Loisel, lead author of the paper produced from the research.

One of the ways black holes are studied by us here on Earth is through the observation of X-rays emitted by the energized materials, like iron and silicon ions, within accretion disks.

These observations allow us to calculate the size of and speed at which the black hole is spinning.

Here’s where it gets tricky: The findings of the Sandia experiment essentially concluded that if no X-rays are detected coming from materials within an accretion disk, they aren’t there.

The Sandia Z Machine in Albuquerque is part of the Pulsed Power Program, which started at Sandia National Laboratories in the 1960s. (Source: Sandia National Laboratories)

That sounds simple and straightforward enough, but the standing theoretical assumption – called the Resonant Auger Destruction assumption – proposed an explanation for why, even though an ion might be present, we might not be able to observe X-rays being emitted from it within an accretion disk. (Auger is pronounced o-ZHAY and refers to its French discoverer.)

“In the past, early models assumed there was this process called Resonant Auger Destruction that will kill the light,” said Javier Garcia, a postdoctoral scholar at the California Institute of Technology and the world’s leading expert on modeling the X-ray spectra of black holes.

By “light,” Garcia means X-rays; an X-ray is actually light that is too energetic for our eyes to see.

The assumption was originally made around two decades ago.

The Auger assumption said that instead of releasing photons, or light particles, to return to a lower energy state, the ions within accretion disks shed their own electrons, which would not create photons.

But upon re-creating the ideal circumstances for the phenomenon to be observed and using advanced instrumentation, the Sandia researchers found that if there are no photons present, the ion isn’t there either.

So what does the death of the Resonant Auger Destruction assumption mean for the scientific community?

Previous research that took Resonant Auger Destruction into account in modeling black holes may need to be tweaked.

That probably won’t mean much to the layperson.

What’s astounding, Garcia said, is the achievement of performing the experiment itself.

“The most dramatic part is them re-creating the conditions near a black hole,” Garcia said. “This paper is just one little taste of what we can do.”

Disproving the Resonant Auger Destruction assumption is a perfect example of how science is supposed to work.

Someone comes up with a theory, experiments are conducted and the theory is refined or disproved, Loisel said.

“We are really humble about what we can know,” Loisel said. “We have a theory; we think that’s how things work until we are proven wrong.”