Laura Sales first fell in love with astronomy when she was in middle school in Argentina, her country of birth. Today, she is an assistant professor of physics and astronomy at UC Riverside and the recipient of the National Science Foundation’s prestigious Faculty Early Career Development (CAREER) Award, one of the most coveted recognitions a young faculty member can receive.
The five-year award supports early-career faculty who have the potential to serve as academic role models in research and education and build a firm foundation for a lifetime of leadership in integrating education and research.
When she received news of the award, Sales couldn’t help recalling how in middle school her geography teacher made her class study the solar system, with close attention paid to each planet.
“I was immediately hooked,” she said. “I remember going through the chapter on the solar system quickly. I did not want it to end. I even walked home from school reading the rest of the book.”
Soon after, a biweekly collectible edition on space, comprised of a magazine and a VHS tape on the mysteries of the universe, began arriving at bookstores. Sales managed to purchase the entire collection.
“I watched each video several times,” she said. “The videos inspired me to study the universe for the rest of my life.”
With the nearly $720,000 CAREER Award she has received, Sales will be doing just that. Specifically, she will study dark matter — a mysterious nonluminous material in space — that is understood to constitute 85 percent of the matter in the universe.
“The nature of dark matter is unknown and understanding what it is made of is one of the most important leading challenges in physics, astrophysics, and cosmology,” Sales said.
The CAREER Award will allow Sales to study the dark matter content of dwarf galaxies found in major concentrations of galaxies astronomers refer to as clusters. Dwarf galaxies are small galaxies that contain between a thousand to a few billion stars. In contrast, the Milky Way has 100-400 billion stars. Dwarf galaxies are the most abundant galaxy type in the universe and often orbit larger galaxies.
“The most successful theory we have about dark matter is the Lambda Cold Dark Matter, or LCDM, model, which makes predictions that agree remarkably well with our observations and experiments on astronomical scales,” Sales said. “As we move toward smaller scales and low-mass galaxies, however, these predictions begin to deviate from observations. Only by observing small galaxies can we learn more about dark matter and refine and correct our theoretical models.”
Sales explained that the specific nature of dark matter defines not only the behavior of stars in galaxies, but also dictates how the universe evolved from tiny fluctuations in mass after the Big Bang to the spectacular collection of galaxies, groups, clusters, filaments, and other structures that populate the universe.
Her research team also plans to use hydrodynamical simulations to determine the many paths by which dwarf galaxies start and stop forming stars in high-density environments.
“Such simulations can successfully bring us a step closer to understanding how exactly the faintest galaxies form and evolve in the universe, particularly in complex high-density environments such as clusters,” she said.
Laura Sales (second from left) is seen here, from left to right, with graduate students Omid Sameie, Ethan Jahn, Lydia Elias, and Jessica Doppel. (UCR/Stan Lim)
Sales is most interested in addressing one question that relates to the different morphologies of the smallest galaxies. She explained that observations show that the stellar mass of a galaxy correlates well with the size of the galaxy. For example, more massive galaxies are more extended than smaller ones.
“This has been the standard bread-and-butter of galaxy formation models for decades,” she said. “This completely breaks down, however, if we look at dwarf galaxies that have about a thousand times fewer stars than our Milky Way. For these dwarfs, the mass in stars says nothing about their sizes. Two dwarfs with similar stellar content can be up to 100 times different in radius. We suspect that dark matter and star formation play a leading role in defining this, but we don't really know. Our simulations will attempt to answer this particular question also.”
Sales received her doctoral degree at the Universidad Nacional de Córdoba in Argentina. Subsequently, she held prestigious postdoctoral fellowships at the Max Planck Institute for Astrophysics in Germany and at the Center for Astrophysics at Harvard University. She joined the UCR faculty in 2015. Two years later she received a Hellman Fellowship.
The CAREER Award Sales received will support two graduate students and summer internships for several undergraduate students. Sales’ group will also run a summer program for high school students in the Riverside area; the students will take and analyze astronomical images. The grant will also make possible the purchase of state-of-the-art computational nodes to run demanding numerical simulations.
“Our research will foster important collaborations with other institutions, in particular, with the Max Planck Institute in Germany, Harvard University, and the Massachusetts Institute of Technology,” Sales said.