How black holes answer our biggest questions
Erin Hicks, professor in UAA’s Department of Astronomy and Physics, is asking some really big questions — perhaps the biggest question that has ever existed — why are we here?
She may be one step closer to finding the answer.
Last fall, Hicks and her collaborators were awarded observation time on the James Webb Space Telescope (JWST) for two research projects to be carried out as part of a larger effort known as the Galactic Activity, Torus and Outflow Survey (GATOS). Hicks’ JWST research time is focused on studying supermassive black holes. This summer, JWST began providing Hicks and her team with photos and data.
Hicks’ research with JWST focuses on the relationship between galaxies and the supermassive black holes at their centers. Despite their terrifying nature, black holes are a critical component of the formation of galaxies and possibly have a profound impact on the universe’s evolution.
“My piece of the puzzle is understanding why in some galaxies the black hole is growing and what impact that has on the galaxy,” said Hicks. Much of her work has focused on determining the connection between a galaxy and its black hole by tracking the motion of gas and stars in the vicinity of a black hole by observing light emitted by excited gas and stars and the shifting of this light as they move. “Through observations we know a connection exists [between galaxies and black holes], the physics of how this connection is created is what we don’t yet understand.”
For decades, astronomers and physicists have had access to high-powered telescopes. The problem is that most of these are located on Earth, and the planet’s atmosphere limits scientists’ view of the cosmos. With the launch of JWST in December 2021, astronomers will have the most precise infrared picture they’ve ever had of the universe.
Popular culture has categorized black holes as all-consuming cosmic monsters swallowing whole galaxies and any unfortunate object that crosses their path. The truth is more nuanced than that. While black holes are incredibly powerful and have the ability and tendency to suck objects like galaxies into them, we’ve learned recently that not everything ventures across their fateful event horizon. There’s a bit of a buffer zone Hicks characterizes as the central region.
“Getting into the black hole is hard,” Hicks said. “A lot more happens with materials instead of just falling straight in. There is a lot of physics involved for materials like gas and dust to move down into the central region; physics she and her colleagues are still trying to work out. “This material slowly spirals down into the central region and then kind of bunches up. It doesn’t just fall straight into the black hole.”
Evidence suggests the central region holds a massive amount of material like gas and dust, all moving at high velocities, creating a zone between us and a black hole. While scientists knew the central zone existed, with JWST photos and data, they can firmly say it exists and that not everything traveling toward the center of a black hole actually goes in. Some of it remains in this central region. Because of the incredibly powerful energy created in this zone, sometimes materials get spewed back out, which could be powerful enough to be galaxy-altering, even possibly universe-altering. These are the big questions Hicks and her colleagues are trying to figure out: what is the central region, what materials live in this zone, what is it all doing there and why isn’t it being sucked into the black hole?
“Now we’re able to look at those central regions and can see how it moves, what are the conditions and what has to happen to the material in that region before it can go into the black hole,” said Hicks. The bigger question is whether there is potential for energy from the central region to be transferred back into a galaxy. “All this energy is released before the material gets into the black hole that creates these strong jets and winds that can change a galaxy.”
With data from JWST, Hicks and her colleagues can tackle the question of how a black hole impacts a galaxy and whether it plays a role in helping to create one or possibly the roles black holes played in the creation of the universe.
“It really changes our perspective of black holes, they’re not just consuming a galaxy, they are also putting out a tremendous amount of energy that changes a galaxy and how it looks,” she said. “So the galaxies we see today look that way in part because the black holes at their center had this period of rapid growth and during that process released a massive amount of energy forever changing the galaxy it resides at the center of.”
Hicks is on sabbatical for the academic year and is excited to dive into the data that JWST is already pumping out before she returns to the classroom next fall. While she is excited to dig into her research, she’s even more excited about sharing it with her students. After all, despite being on the frontier of astrophysics, Hicks is a teacher at heart.
Those students will be working on groundbreaking research that may alter our understanding of the universe and how galaxies are shaped and formed, ultimately getting us closer to answering the big question: Why are we here? ““It’s gratifying to provide an avenue for students to engage in research and offer them an authentic research experience,” said Hicks. “Our undergraduate students will have the opportunity to contribute to true scientific discovery and explore the universe in which we all live.”
A version of this story appeared on UAA’s Green & Gold News website earlier this year.