A Bridge to Chasing Active Galactic Nuclei

John Hood II, APS Bridge Program graduate, achieved a dream he once thought impossible.

By Rachel Crowell | April 13, 2023

Astrophysicist John Hood II, who received his doctorate in 2022.

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At the centers of most large galaxies, supermassive black holes lurk, pulling in matter and blasting out unusually bright bursts of light.

These luminous areas are called active galactic nuclei (AGN), and astrophysicist John Hood II, a postdoctoral researcher at the University of Chicago and Kavli Institute for Cosmological Physics, and a National Science Foundation Office of Polar Programs Fellow, can’t get enough of them.

"I feel like the thing that's most exciting about [AGN] to me … is there are a lot of questions, but not a lot of solid answers,” says Hood, who received support through the APS Bridge Program, which helps underrepresented minority students prepare for graduate school in physics.

As a Boy Scout in Columbus, Georgia, Hood became enthralled with stargazing on troop camping trips. And on trips to visit family in rural Alabama, he would study the “weird-looking clouds” in the night sky — clouds lit, he learned, by stars.

While those experiences kindled his passion for astronomy, some comments dampened it. "As I got older, I fell into the trap of being told, 'Oh, you're not good at math, so there are certain things you can’t do,’" Hood says.

When he entered college at Columbus State University in 2009, he majored in aerospace engineering instead. "I was always told I was good with my hands, good with building things and taking things apart, so engineering made sense," he says. But when his girlfriend — now wife — took him to a university-sponsored astronomy event where attendees could use telescopes to view stars, everything changed.

"It was one of the best birthday presents ever," Hood says. Realizing he already met the prerequisite requirements, he dove into "a two-part class of Astronomy I and Astronomy II in the same semester." The professor, Shawn Cruzen, "became very influential in my life and career," he says.

"After the first half of the semester, he pulled me aside one day and was like 'Have you ever considered studying astrophysics? You have a real knack for this," Hood says. He remembers "audibly chuckling."

"I was like, 'Doing astrophysics? There's no possible way!" he says. Cruzen proposed a game plan. "Change your major to astrophysics, take a couple of the classes, see how you like it, and if you don't like it, I'll help you change your major back," Hood remembers him saying. Hood made the shift and never looked back.

But when he applied to graduate school, he received six rejections. "I was in a really deep funk," he says. However, one rejection letter came with a suggestion: Apply to the APS Bridge Program.

Applying was nerve-wracking. "You don't know where you're going to go,” he says. “Any of the Bridge programs could pick your application.” But he felt he had to take the plunge. "I really want to chase this dream,” he recalls thinking.

In 2015, a year after earning his bachelor’s degree, he enrolled in the Fisk-Vanderbilt Master's-to-PhD Bridge Program. He says that program had an "almost immeasurable impact." At Columbus State, "my first time meeting a Black scientist was right before I graduated," he says — but at Fisk University, an HBCU, he realized, "I'm not alone out here. There are other people interested in the same thing that look like me." The mentorship he received was invaluable, he adds.

Immediately, Hood was convinced he wanted to study active galactic nuclei. "That was the one thing that I knew," he says. He decided to find "anybody who's studying black holes” and “stick to them like a puppy." One such person was Kelly Holley-Bockelmann, his faculty advisor in the Bridge Program who later became one of his doctoral advisors.

Jedidah Isler, then a postdoctoral researcher at Fisk University, became his research advisor for his master's research. "We were doing multi-wavelength observations of AGN from gamma rays to optical and infrared," Hood says. He was transfixed.

After earning his master's degree in 2017, he began his doctoral program at Vanderbilt University — but there was a hurdle. "[Holley-Bockelmann] knew that I was interested in experimental work, and she was like, 'Well, we don't really have anybody here that does that. But we can find somebody who's willing to take a student who has funding,'" he recalls. They eventually landed on Stephan Meyer at the University of Chicago.

There, Hood worked with the South Pole Telescope (SPT) Group, as well as CMB-S4, an international experiment on the cosmic microwave background. "I was doing detector development work with them ... Getting my hands dirty in the lab, learning how to run the cryostats, learning how the detectors work, learning how to manufacture them and make them better than the current ones,” he says. “It was just a lot of fun."

When Thomas Crawford, his faculty advisor, mentioned that some researchers wanted to use SPT data to study active galactic nuclei, Hood's experience was a boon. Hood is first author on an AGN-specific analysis paper using SPT data, which was recently accepted to The Astrophysical Journal. He received his doctorate in 2022.

In his current position, Hood is continuing that work, and he plans to share the data on a public website. He's also exploring statistical analysis. "We're trying to study the connections between the variability at different wavelengths of AGN," he says. The recent paper represented just one source — or potential AGN — and "we have over 100 sources that we could possibly look at," he notes.

Hood's advice to students in astrophysics and beyond? "Do what you feel you have some sort of passion for, because that makes everything easier." And for anyone considering the APS Bridge Program, his guidance is even simpler: "Do it.”

Rachel Crowell is a math and science journalist based in Iowa.