Hunting for relics of a universe past

Some 14 million years ago, a cluster of stars collapsed and exploded into a shower of supernovas, sending a burst of gas racing across the sky. Some of the smaller stars survived the destruction, many of them orbiting not too far from Earth today.

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These stars hold secrets about the cataclysmic explosion they witnessed, information that can improve models of the ways stars form—and perhaps reveal clues to one of the universe’s greatest remaining mysteries: the nature of an invisible cosmic material called dark matter. This mystery is why rising second-year Mariam Tskitishvili is spending her summer sorting through data from the European Space Agency’s Gaia telescope. 

Tskitishvili is one of two undergraduates working with Robyn Sanderson, an associate professor in the Department of Physics and Astronomy in the School of Arts & Sciences, this summer. The 10-week internship, run through the Penn Undergraduate Research Mentoring (PURM) program of the Center for Undergraduate Research and Fellowships, offers each student a $5,000 stipend for hands-on experience and a chance to test out their field of choice.

Tskitishvili, who is majoring in physics with a concentration in astrophysics, had hoped to find a summer project that brought together her interests in studying the universe and learning to work with data. Sanderson’s lab offered just that combination. She has been poring over records of these stars to retrace their paths since the explosion. She can then match those journeys with data from the Gaia telescope, which has observed almost two billion stars in the Milky Way galaxy, looking for those located in the correct part of the sky and moving at the correct velocity to indicate that they were part of that explosive cluster.

After taking Introduction to Astrophysics with Sanderson her second year, rising third-year DiMauro knew she’d found the field she wanted to work in, so she applied for a PURM internship with Sanderson’s lab. DiMauro’s project stems from Sanderson’s goal of using information about star orbits to narrow in on the nature of dark matter. Researchers know dark matter exists because they can see its gravitational pull on objects in the universe, like the stars in galaxies, but they don’t yet know what it’s made of. By more precisely measuring its effects on visible matter, they can eliminate possibilities about its nature.

Using a National Science Foundation supercomputer called Frontera at the Texas Advanced Supercomputing Center, DiMauro is analyzing simulations—each one taking about a month of supercomputer time and 10 terabytes of data, equivalent to about 10 million novels—of how different theoretical forms of dark matter affect these galaxy strings.

For DiMauro, the research fellowship is a chance to see whether astrophysics research is the right fit. “Doing this work has given me such a strong feeling of accomplishment,” she says. “Because dark matter is what sold me on astrophysics originally, this project has felt almost full-circle.”

Read more at Omnia.