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JMU student research makes landmark blackhole discovery
When Jenna Harvey decided to give physics and astronomy a try, she had no idea her research would contribute to a historic discovery — three galaxies containing supermassive black holes on a collision course — a discovery that proved a long-held theory and gained international news attention.
She only settled on majoring in physics and astronomy after trying other sciences and feeling bored. There was something about an introductory astronomy course that clicked, and after Harvey learned to understand data supplied by a researcher at the Large Binocular Telescope in Arizona, she realized something interesting was happening. There were signs indicating that two of three galaxies dancing around each other contained supermassive black holes that were actively snacking on their surroundings.
“Basically the data is plotted like the light intensity at each wavelength,” Harvey said. “It looks like a bunch of squiggles.” What Harvey noticed in those squiggles were patterns that indicated hydrogen gas moving at near the speed of light, which only happens around supermassive black holes.
A black hole is a region of spacetime where gravitational acceleration is so strong that nothing, including light, can escape. Researchers find black holes by observing what's happening around them, such as the movement of hydrogen gas. "In the distant galaxies, you can get spectra measurements like Jenna is working on and follow the gas and find out how fast it’s moving and if that motion happens at relativistic speed, just a fraction of the speed of light, there’s nothing else that can produce that kind of motion, so then that’s an active galactic nucleus,” said Anca Constantin, an associate professor of physics and astronomy and Harvey’s advisor on the project. “If there’s an AGN, there’s a supermassive black hole that’s actively feeding on the surrounding material.”
Constantin, who is part of a collaboration that includes George Mason University, said Harvey’s discovery “was kind of the nail in the coffin” for confirming that two of the three colliding galaxies have black holes that are actively growing, a process that has been predicted theoretically to be triggered by galaxies smashing into one another. George Mason researchers definitively identified the third black hole using X-ray data from the Chandra X-Ray Observatory. They needed additional data from the near-infrared spectrum to confirm the other two, and that’s where Harvey came in.
The consortium asked Dr. Barry Rothberg at the Large Binocular Telescope Observatory for the near-infrared data that Harvey reviewed.
“Dr. Rothberg had already cleaned up and reduced the data for me before I started looking at it,” she said.
Harvey said her contribution to the research was "a little bit surreal, honestly. I didn't think this was going to happen."
In addition to the Large Binocular Telescope and the Chandra X-ray Observatory, data for the discovery came from the Sloan Digital Sky Survey and NASA's Wide-field Infrared Survey Explorer.
Constantin said the discovery has created excitement throughout the field of astronomy. Three black holes colliding has been predicted but never confirmed.
Harvey is continuing her research. "That one triple is from a collection of 15 total galaxy mergers that I have been looking at," she said. "Looking at all of them is what I was doing over the summer and it just happened that the data for the triple was really relevant for this research."
The JMU Department of Physics & Astronomy, with 20 faculty members and more than 120 students, strives to be a leading undergraduate physics and astronomy department by building a research-active, student-centered community. More information about the department can be found on its website.
Involves Faculty, Involves Students
January 31, 2020
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