Quasar light reveals galaxy ‘fingerprints’

New research is using the light from quasars to reveal the chemical fingerprints of stars and unlock the secrets of galactic evolution.

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Spiral galaxy M81 as a composite image taken by NASA’s Spitzer and Hubble space telescopes and NASA’s Galaxy Evolution Explorer. Image Credit: NASA/JPL-Caltech/ESA/Harvard-Smithsonian CfA


Astronomers could be a step closer to understanding how the Milky Way and other galaxies formed, following new research that uses quasar light to uncover galactic fingerprints.

PhD candidate in physics and astronomy at the University of Victoria Trystyn Berg is working with collaborators to study distant galaxies that were created during the first three billion years of the Universe, and which lie over 50 billion lightyears away.

Using the Keck telescope, the team have analysed 30 distant galaxies, adding to a previous sample of 310, and compared their chemistry to almost 2,000 stars within six nearby galaxies, including our own.

To view these distant galaxies, the team look for quasars; energetic, distant points of intense light. Observing these quasars enables them to discover how a galaxy evolved, how many stars it has and the types of stars it has created.

“Stars are the cauldrons of the universe,” says Berg.

“They create the elements we’re made of. They consume their fuel and release the products back into the galaxy during supernova explosions.

“All of the gas within the galaxy will absorb some of the background quasar light, leaving a fingerprint of which elements are within the galaxy.

This chemical fingerprint can give us some very useful clues about the evolutionary history of the galaxy.”

Berg and the team are the first to compare data collected on distant galaxies with those nearer to the Milky Way.

“We found that many of the distant galaxies are similar to low-mass galaxies in our neighborhood,” he says.

“It’s incredible to see, in the short time of three billion years, how quickly it took the Universe to make the building blocks of the Milky Way system.

“These observations are stepping stones that allow us to tag which early galaxies the stars of modern galaxies came from.


We still don’t have an understanding of how parts of the Milky Way system formed, and our results now tell us what chemistry to go look for to answer this question.”