UNLV professor gets to observe rare astronomical event

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Bing Zhang is one of those guys who figured out what he wanted to do with his life when he was a kid.

“Every child,” he said, “is fascinated by the stars.”

He grew up in China. He’d had an interest in science and science fiction as a youngster, but it was in his second year of high school when he came across a story about Albert Einstein.

He learned that one man with a brilliant mind could change everything.

And so that is what Zhang set out to do.

He became one of the world’s leading researchers on gamma ray bursts. (We’ll explain those later.)

“Gamma ray bursts are a very weird phenomena,” Zhang said.

So now, it is decades later, and Zhang has just finished teaching an introductory astronomy course with 160 students in it at the University of Nevada, Las Vegas .

He fingers through a computer printout of a game-changing article published last week in the journal Nature with his name at the top.

“Relativistic jet activity from the tidal disruption of a star by a massive black hole.” That’s the title.

NASA, in a news release, called the event the article and another related one detail “truly extraordinary.”

The article itself says things like, “For a black hole of this size, the peak isotropic X-ray exceeds the Eddington luminosity …”

Zzzzzzzz.

Nature is, after all, one of the world’s leading scientific journals. It is geared toward hard-core scientists who don’t necessarily speak the same language everyone else does. They don’t need catchy headlines and simple words that the general public will understand.

So, what does it mean?

It means that Zhang and an international team of scientists have essentially just watched a supermassive black hole at the center of a galaxy in the constellation Draco swallow a star and shoot a powerful jet of light and radiation straight at the Earth. (Don’t worry, it won’t hurt you.)

This happened 3.9 billion years ago, when the Earth was still in diapers.

Because the light had to travel so far — right about 20 billion trillion miles — the scientists saw it happen just this past March.

No one has ever seen it happen before. No one was even sure this sort of thing actually did happen until this team saw it.

In fact, even they weren’t sure that’s what they were seeing at first.

That’s often how science works.

It is Zhang’s job to analyze the data. He’s a theoretical astrophysicist.

He came to America after his education in China because, he said, this is where the world’s best scientific opportunities are.

He joined a division of NASA, then hopped to Penn State University, where he was a researcher. Yearning for a more permanent position, he came to UNLV in 2004. He has since earned tenure as a professor.

Along the way, Zhang joined a team of scientists whose job is to respond when a specialized satellite captures images of gamma ray bursts.

These are massive bursts of a certain kind of radiation and light. They’re super bright, and they can be detected from Earth’s orbit if the burst happens to be facing this way.

They occur when a star collapses in on itself and dies. That’s called a supernova.

The point of studying all of this is to figure out how the universe works, nothing less. It’s unlikely anyone’s going to use this knowledge anytime soon to build a better toaster.

But someday, someone might.

So anyway, back in March, an alert went out after the satellite detected what everyone thought was a new gamma ray burst.

Then the data began to come in. Hmm, Zhang thought. Something is not quite right. This thing wasn’t acting like a gamma ray burst. The timing was off, as was some other data.

“When this happened,” Zhang said, “we figured it must be something else.”

Supermassive black hole? Could be. They’re in the center of every galaxy.

Maybe, Zhang thought, this supermassive black hole was swallowing a star as they watched.

The team sought more data. They found more evidence. They did loads and loads of calculations and, sure enough, they convinced themselves they had just witnessed an entirely new phenomenon .

“It’s just a fascinating subject,” said UNLV’s dean of sciences, Tim Porter, a physicist by training.

He said the university’s reputation as a research center is growing, and the publication of the paper Zhang co-authored in one of the world’s top two or three scientific journals is a big deal.

“It’s kind of a hidden fact about UNLV that we’ve achieved this over the years,” he said. “Most people don’t realize. They think, oh, UNLV. They have a good basketball team. The hotel school. But we’ve made great strides in so many areas.”

Like astronomy. When Zhang came, there was just one professor. Now there are three . The physics department is now the physics and astronomy department.

So an up-and-coming scientist at an up-and-coming university was part of an international team that discovered something no one knew existed.

Which raises the question: Why did no one know this existed?

Scientists had seen what they believed were the aftereffects of black holes swallowing stars before. They were all pretty sure of it. But they didn’t even know the whole burst-of-light-and-radiation thing happened.

And this black hole? It’s gigantic. About a million times the mass of our sun. That’s why it’s called a supermassive black hole.

Zhang said it’s been swallowing stuff for billions of years, but probably not much lately. So there was nothing to see, no data to measure, for eons and eons.

But then, for whatever reason, this particular star wandered too close and, well, it got sucked into the massive gravitational field.

There’s no way around the physics of that.

Contact reporter Richard Lake at rlake@reviewjournal.com or 702-383-0307.