University of Wyoming grad student studying black holes
Nov. 29, 2017
LARAMIE, Wyo. (AP) — University of Wyoming graduate student Michelle Mason remembers third grade as the best year for science during her K-12 education.
"We learned about the ocean, we learned about volcanoes, we learned about dinosaurs, and learned about the solar system," she said, ticking off the topics on her fingers.
Mason needed only a taste of the wonders outside Earth's atmosphere to set the trajectory of her professional career.
"I decided at 9 years old that I was going to learn everything there is to know about the universe," she said. "Absolutely everything."
She might have adjusted her goal slightly in the interim, but the passion remains for Mason, these days directed at the farthest edges of the universe and some of its most mysterious and powerful objects.
Working on a Ph.D. in the UW Department of Physics and Astronomy, Mason's focus is objects known as active galactic nuclei, which she described as "supermassive black holes at the centers of very distant galaxies."
Most galaxies have a supermassive black hole at their center. An active galactic nucleus, also called an AGN, is a supermassive black hole that emits energy across the electromagnetic spectrum. The most powerful are known as quasars, some of the brightest objects in the universe.
Mike Brotherton, an astronomy professor and Mason's adviser, said quasars can be thousands of times brighter than the galaxies they reside in.
"They're awesome," he said.
Mason grew up in the San Francisco and studied astrophysics at the University of California, Berkeley. In 2012, she spent the summer in Laramie participating in UW's Research Experience for Undergraduates.
Through the program, funded by the National Science Foundation, students convene at sites around the country to work on research projects with faculty and other scientists. At UW, Mason and several other students learned about AGNs.
"I just fell in love with them," she said.
Up to that point, her undergraduate focus had been supernovas, which are exploding stars. She turned her attention to black holes, which are formed by collapsing stars.
"I am very interested, basically, in how things die in space," she said.
At the same time, scientists wonder if black holes, specifically AGNs, are also the key to creation of new galaxies.
"Could these things that are known to be monsters of destruction actually be the source of creation of everything that we see in the universe?" Mason said. "It's an ongoing question."
A black hole is a region in space with such a strong gravitational pull that nothing can escape it, not even light. They were theorized to exist as far back as the 18th century, but not until the 20th century did scientists demonstrate their existence using the theory of general relativity.
A star reaches the end of its life cycle when the process of nuclear fusion at its core consumes the available elements. Without fusion creating outward pressure, the star can no longer withstand its own gravitational pull.
"It gets too heavy and collapses in," Mason said.
The entire mass of the star collapses to a point of great density called the singularity, which has enough gravitational pull to warp space-time. Mason said scientists wonder if they lead to other dimensions or different universes.
Scientists also theorize that if an object were to approach a black hole, the extreme forces would pull the front at an ever-faster rate than the back in a process called spaghettification. Yes, it's real term.
"Black holes are bending space-time so much that we can't really describe what's going on inside, which is one reason I love them," Mason said.
As for supermassive black holes — which have the mass of thousands, millions or even billions of stars — scientists aren't sure how they form. But they know that almost every massive galaxy has one at its center, even the Milky Way.
Which takes us back to AGNs. An active galaxy has a supermassive black hole at its center that's pulling material toward itself. This material collects around the black hole as an accretion disc, with more gas and dust surrounding the disc farther out. Gravity and friction cause the accretion disc to heat up and emit radiation.
"The black hole is eating a bunch of material, and that is releasing a lot of energy and a lot of wind, which blow away from the black hole," Mason said.
Quasars are AGNs that emit huge jets of light, perhaps created by magnetically charged particles. These jets are also a source of radio waves, which was what led scientists to find them and inspired their name, short for quasi-stellar radio object.
The radiation emitted from the AGN acts as a shock wave, which could cause gases away from the black hole to condense and form into stars, in turn creating a galaxy, Mason said. Eventually, the supermassive black hole grows quiet, leaving a galaxy of stars in its wake, according to the theory.
Scientists gather information about quasars using massive telescopes more than eight meters in diameter.
"Quasars, even though they're very bright, are very, very far away," Mason said.
Her current work involves examining the near-infrared spectra of quasars that have already been cataloged, with the goal of having better data for scientists to use.
"We have a lot of optical data, but we don't have a lot of infrared data," Mason said. "I'm working on getting a very uniform set of data."
The aim, according to Brotherton, is a more complete picture of known quasars
"It should eventually help us better determine their black hole masses and other properties," he said.
Mason said AGNs are the key to understanding the events following the initial creation of the universe.
"We've pretty much sorted out how the Big Bang happened," she said. "But after that, what happened? These things are the key for that next step in cosmic evolution."
Brotherton said science is slow work, but Mason has the persistence necessary to match her curiosity.
"Conducting original research requires putting in the time and effort not just over a few hours or days, but months or even years," he said.
Mason is also pursuing a master's degree in education, and she hopes to teach after she finishes her Ph.D.
"I'm a firm believer that all the knowledge in the world means nothing if you can't pass it on and you can't make it important to other people," she said.
As she leads the next generation of young scientists to take up the mantle of deep space discovery, perhaps one day everything in the universe will be learned.
Information from: Laramie Boomerang, http://www.laramieboomerang.com