Galactic archaeologist UVic awaits key cosmic insights from Chilean observatory

Galactic archaeologist UVic awaits key cosmic insights from Chilean observatory

World’s largest digital camera aims to increase understanding of dark matter and distant dwarf galaxies

While Jaclyn Jensen spent part of her undergraduate studies in France, her time studying abroad happened to coincide with the time when the Gaia telescope in space began delivering astronomical data.

The experience helped fuel her interest in the origins of the Milky Way and how it formed. The University of Victoria PhD candidate is now among a group of astronomers whose efforts to reconstruct the history of space have earned them the nickname galactic archaeologists.

“I think the biggest question we all have is, ‘How did we get here?’ or ‘Where did we come from?’” Jensen said in an interview.

Just as archaeologists dig through rubble to unravel mysteries of the past here on Earth, astronomers use features of ancient stars – such as their elemental abundance and how they orbit Earth – to create a kind of fossil record of galaxy formation.

“In galactic archaeology we use these facts to reconstruct the history of the Milky Way through time.”

In the coming years, Jensen’s field of cosmology is likely to receive a new boost from a new facility in Chile that could shed more light on the darker aspects of space.

Equipped with the world’s largest digital camera and a telescope with an exceptionally wide field of view, the Vera C. Rubin Observatory will provide deeper views of the universe, advance our understanding of dark matter and map the entire sky of the Southern Hemisphere in just three nights.

Jensen’s research focuses on the dwarf galaxies that orbit the Milky Way and how they are destroyed and then accreted into the system we call home. As the smaller orbiting galaxies disintegrate, they leave behind trails of stars that form string-of-pearl structures called stellar streams.

The Chilean observatory and its car-sized camera will be exciting because it will detect superfaint structures that will help fuel many new discoveries about dwarf galaxies and stellar streams, Jensen said. That’s partly because of the yet-to-be-completed facility’s potential to advance our understanding of dark matter.

That matter doesn’t give off light or emissions, so it can’t be observed, but scientists can still record the influence of gravity on other visible objects. Dark matter has many implications for the UVic astronomer’s research because it makes up a large fraction of the Milky Way’s mass, which affects the gravity that dictates the orbiting stars in our galaxy.

“The interesting thing about stellar streams is that their path, their orbit, and their position on the sky are actually indirect detections of the distribution of dark matter in the galaxy,” Jensen said.

Despite the fact that dark matter was present at the time of the Big Bang and played a major role in the distribution of galaxies, the astronomer says dark matter remains one of the greatest known mysteries.

“It’s clear that this is a fundamental part of the universe that has been with us for eternity, and we hope that by better understanding dark matter we can unravel the misunderstood physics that governs our universe,” Jensen said.

Dark matter is also a major factor in galaxies that evolve via the consumption of smaller, distant systems, she added. With Rubin’s large scans of the sky poised to provide more dark matter data, the UVic student is interested in seeing if the early stages of stellar outflow can be observed. Another possibility that excites her is seeing individual stars that were consumed by a dwarf system.

Scientists believe that dwarf galaxies, like Earth’s solar system, also formed by the accumulation of smaller systems. Astronomers still don’t know how big a dwarf system is, Jensen said. The Chile observatory’s ability to detect stellar streams and dwarfs that are too faint for current telescopes could help expand that understanding.

“My research aims to answer the question of how many of these dwarfs in the Milky Way have had another dwarf in the past,” she said.

While she wants to unravel more about the universe’s past, Jensen said the present is an exciting time to be in astronomy, as the observatory in Chile follows the launch of the Euclid and James Webb Space Telescopes. The Rubin site is expected to become operational next year, before publicly available data is expected to start flowing in 2026.

“It will be on everyone’s mind and I’m really interested in using it.”