Roughly a decade ago scientists detected a new sort of brief yet powerful flashes of light from outer space that have come to be known as fast radio bursts (or FRBs). Ever since, astronomers have been trying to understand why these mysterious phenomena occur. A crucial clue to the source of these elusive bursts was explained in a Nature paper earlier this month—one that was co-authored by a Haverford College senior.

Astrophysics major Matthew Abruzzo '17 spent last summer working with a team at Cornell University's Research Experience for Undergraduates (REU) Program. The goal was to get some hands-on research experience and utilize some of the techniques he had learned in his Haverford astronomy courses. The result, however, was getting to be a part of a team that published cutting-edge research in a leading journal. (He worked with a trio of investigators at Cornell, including the Nature paper's lead author, Shami Chatterjee.)

In the paper, the team localized one particular burst (FRB 121102) to a particularly small region in the sky thanks to the use of the Karl G. Jansky Very Large Array, a network of 27 radio dishes in New Mexico which acts as an interferometer. Localizing this burst was possible because, of the roughly 18 known FRBs, it is the only one astronomers have seen repeat.

"The paper discusses the co-location of the FRB with a persistent radio source and a very faint optical source, and the spectra of the bursts—the brightness at different frequencies," said Abruzzo. "Additionally, the paper concludes that the source must be originating from outside of our galaxy."

"It is remarkable to have confirmed that this burst really did originate a substantial fraction of the way across the universe," says Haverford Senior Postdoctoral Research Associate and Visiting Assistant Professor of Astronomy Alex Hill. "The fact that it’s in a fairly unremarkable galaxy—much smaller than our Milky Way—suggests that these bursts may be present-but-unseen all over, but also makes them all the more mysterious. How could a source produce so much energy so quickly in such a small galaxy?"

Because this new information now rules out many of the different FRB models, astronomers now believe that the explanations for these millisecond-long pulses of radio waves must either involve a neutron star located within a young supernova remnant or an active galactic nucleus.

At Cornell, Abruzzo's job was to detect all of the radio sources in the region thought to contain FRB 121102 and construct light curves for each of them, which involves plotting how their brightness changes over time. He studied the variability of each source on timescales of days to weeks.

"It turned out that one of the 76 radio sources I had detected was the persistent radio source co-located with the fast radio burst," he said. "The collaboration used my light curves to investigate the properties of the counterpart, as well as to assess variability of other sources in the field."

"Matthew’s success in jumping in to a new project as an REU student and making such a substantial contribution in a summer is very impressive," said Hill. "Typically, it takes some time to figure out a new science area. Often, by the end of the summer, students are just getting their feet under them and ready to make real progress. Matthew figured out how to analyze his data, produce results, and find and characterize the relevant source all in one summer!"

Coincidentally, Abruzzo wasn't the only Ford credited on the Nature paper. Sarah Burke-Spolaor '06, a former Jansky Fellow at the National Radio Astronomy Observatory in New Mexico and current assistant professor of physics at West Virginia University, was another of its co-authors, though she and Abruzzo never met and didn't work together. 

-Rebecca Raber