Laura Sales

NSF CAREER Award supports astronomer's quest to further understand the universe

ilseu — Mon, 03 Feb 2020 23:40:04 +0000

NSF CAREER Award supports astronomer's quest to further understand the universe ilseu Mon, 02/03/2020 - 15:40 More College News Eureka Alert | AAAS February 03, 2020

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.

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 Cordoba 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.

The Milky Way galaxy stole a few tiny galaxies from a neighbor

ilseu — Fri, 08 Nov 2019 05:46:15 +0000

The Milky Way galaxy stole a few tiny galaxies from a neighbor ilseu Thu, 11/07/2019 - 21:46 More CNAS in the Media Ashley Strickland | CNN October 10, 2019

CNN online⁠— Our large galaxy, the Milky Way, is orbited by more than 50 other, smaller galaxies. But astronomers recently discovered that some of these galaxies were kidnapped from neighboring large dwarf galaxy the Large Magellanic Cloud.

The Large Magellanic Cloud, so called because it appears like a faint cloud, is also on a collision course with our galaxy. The LMC is fairly new to orbiting the Milky Way, entering our corner of the universe 1.5 billion years ago. It's now the brightest satellite galaxy we have, 163,000 light-years from the Milky Way. Previously, astronomers thought it would hang out in a quiet, long orbit or speed away from the gravity of the Milky Way and move on.

This violent galaxy next door is set for a collision with the Milky Way
The Large Magellanic Cloud will catastrophically collide with the Milky Way in 2 billion years, according to a study published January in the Monthly Notices of the Royal Astronomical Society. The impact, which they believe is long overdue, has a chance of sending our solar system "hurtling through space."

Now, researchers using the Gaia space telescope realized that four ultrafaint dwarf galaxies, as well as two bright galaxies called Carina and Fornax, once belonged to the LMC. But the merger between the LMC and the Milky Way has begun, and our galaxy's more massive nature is using gravity to rip pieces off of the Large Magellanic Cloud and kidnap some of its orbiting galaxies.

This simulation depicts dark matter in white in the top left of the image, while the bottom left shows a galaxy similar to the Large Magellanic Cloud.

The study results will publish in the November issue of the Monthly Notices of the Royal Astronomical Society. "These results are an important confirmation of our cosmological models, which predict that small dwarf galaxies in the universe should also be surrounded by a population of smaller fainter galaxy companions," said Laura Sales, study author and assistant professor of physics and astronomy, at the University of California, Riverside. "This is the first time that we are able to map the hierarchy of structure formation to such faint and ultrafaint dwarfs."

Telescope showcases our galactic neighbor in a new light
This discovery also sheds light on the past evolution of our galaxy. "If so many dwarfs came along with the LMC only recently, that means the properties of the Milky Way satellite population just 1 billion years ago were radically different, impacting our understanding of how the faintest galaxies form and evolve," Sales said.

Although dwarf galaxies are small, they can still be the home of thousands to billions of stars. But some of the tiny galaxies orbiting the LMC don't contain any stars. Instead, they are filled with dark matter, a mysterious particle that comprises at least 90% -- if not more -- of the universe.

Our galaxy is due for a catastrophic collision, study says
The researchers also think that the Large Magellanic Cloud may actually have more satellite galaxies orbiting it than they previously believed. These galaxies may only be made of dark matter and not contain stars.

"The high number of tiny dwarf galaxies seems to suggest the dark matter content of the LMC is quite large, meaning the Milky Way is undergoing the most massive merger in its history, with the LMC, its partner, bringing in as much as one third of the mass in the Milky Way's dark matter halo -- the halo of invisible material that surrounds our galaxy," said Ethan Jahn, study author and University of California, Riverside graduate student.

In the future, the research team will study how galaxies like the Large Magellanic Cloud form stars. This could also be used to help them determine how much dark matter the galaxies contain. "It will be interesting to see if they form differently than satellites of Milky Way-like galaxies," Jahn said.

Supermassive black holes stop star formation in dwarf galaxies

ilseu — Wed, 06 Nov 2019 16:06:51 +0000

Supermassive black holes stop star formation in dwarf galaxies ilseu Wed, 11/06/2019 - 08:06 More CNAS in the Media Alison Klesman | Astronomy online October 18, 2019

ASTRONOMY ONLINE - Astronomers know that most galaxies house supermassive black holes in their centers, from the largest galaxies down to small dwarfs. They also know that when supermassive black holes are actively feeding, they can slow or even stop the formation of stars in their home. Although this relationship has been well established for large galaxies, it has not been studied much in dwarf galaxies. Now, researchers have discovered that black holes in dwarf galaxies are capable of shutting down star formation, just like their more massive counterparts.

In larger galaxies, outflows from supermassive black holes have been linked to the shutdown of star formation. But not in dwarf galaxies. “Typically, winds driven by stellar processes [such as supernovae] are common in dwarf galaxies and constitute the dominant process for regulating the amount of gas available in dwarf galaxies for forming stars,” said first author Christina M. Manzano-King at the University of California, Riverside, in a press release.

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