Local Galaxies Shed Light on Universe's First Stars

Presenting at the 232nd meeting of the American Astronomical Society (AAS) this week in Denver, University of San Francisco (USF) Associate Professor of Physics and Astronomy Aparna Venkatesan will discuss important limits from nearby galaxies on frontier cosmology problems, shedding light on the very first stars in the universe, and how galaxies have assembled and evolved over time.

"Nearby galaxies are a fantastic and understudied laboratory - right in our own backyard - with which to study the early universe," said Aparna Venkatesan, associate professor of physics and astronomy at USF.

"We're essentially laying key groundwork and getting a few years' jump on understanding what the powerful James Webb Space Telescope (JWST) will reveal, by identifying which galaxies near us are the best analogs to early universe galaxies that hosted the very first stars."

The JWST, set to launch in May 2020, is a collaborative mission between NASA, the European Space Agency, and the Canadian Space Agency that will be the scientific successor to the Hubble Space Telescope, offering unprecedented resolution and sensitivity beyond the reach of current instruments. One of its major goals is observing the most distant objects in the universe, including the formation of the first stars and galaxies.

Venkatesan's talk on "Near-Field Cosmology with Low-Mass Galaxies: Constraining the Escape of Radiation from the UV-slopes of Local Galaxies," with collaborators Max Gronke (UC Santa Barbara), undergraduate Mario Olivieri Villalvazo (University of San Francisco), Jessica Rosenberg (George Mason U.), John Salzer (Indiana University), John Cannon (Macalester College), Mark Dijkstra (Stitch Fix), and Chris Miller (University of Michigan), focuses on studying low-mass star-forming systems that can advance studies of primordial star clusters and the underlying physical conditions characterizing early galaxies, one of the target observation goals of the JWST.

In "A Window on First-Stars Models from Studies of Dwarf Galaxies and Galactic Halo Stars," with collaborators L.Y. Aaron Yung (Rutgers), Rachel Somerville (Rutgers/CCA), Gergo Popping (MPIA/Heidelberg), and Jim Truran (University of Chicago/Argonne), Venkatesan explores element genealogy showing strikingly similar element abundance ratios values between nearby dwarf galaxies and ancient stars in the Milky Way's halo, providing critical clues on the important cosmological problems of how and where the first stars formed, how galaxies were assembled and how they've evolved.

"Being able to understand and constrain what the first stars have produced leads us down a path to further understand the origin of the stars," stated collaborator L.Y. Aaron Yung, Rutgers Department of Physics and Astronomy Ph.D. Candidate and former USF physics and astronomy undergraduate. "Essentially, the universe knows what it's doing, and now we're figuring it out."

Venkatesan's findings are a vibrant and unique example of robust research involving undergraduate students, as part of the Undergraduate ALFALFA (Arecibo Legacy Fast ALFA) Team. Her undergraduate research program has won a number of awards, with half of her students going on to STEM careers. "It's a gift to work with the future - these wonderful young women and men - every day, and to mentor these early career scientists who go on to do amazing things."

Related Links
University of San Francisco
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