Jan 19, 2021 - Science

The inner lives of galaxies

Illustration of a hand holding a petri dish that contains a galaxy.

Illustration: Aïda Amer/Axios

The finest details of galaxies — from star explosions to halos of dust — are emerging via new techniques that allow scientists to peer deep into these cosmic behemoths.

Why it matters: How galaxies form, grow and change is key to understanding the evolution of the universe as a whole.

  • By looking at galaxies hundreds of thousands of light-years from us, astronomers can start to turn back the clock to see what our cosmos may have looked like billions of years ago and figure out where we might be heading in the future.
  • Now, "people are looking at galaxies as more holistic celestial objects," Bryan Terrazas, a Harvard postdoc, told me, adding that instead of static snapshots in time, scientists are now seeing galaxies as constantly changing and evolving.

What's happening: A number of studies and recently announced missions are helping to reveal how the inner machinations of a galaxy affect the broader picture of its evolution.

  • Astronomers are starting to think that large amounts of gas expelled into intergalactic space by supernovas or other means may fall back onto the galaxy or even be taken in by others nearby, affecting star formation.
  • Other scientists are looking at how black holes merge when galaxies collide, potentially producing some of the oddly shaped galaxies out in the universe today.
  • NASA advanced its SPHEREx telescope, which is designed, in part, to help piece together how the first galaxies formed stars after the Big Bang.

Be smart: Advancements in technology and analysis tools and the lower cost of space hardware are allowing researchers to push the bounds of what they can actually see and study when it comes to galactic evolution.

  • For example, the future Aspera mission is designed to take a look at the gas environment surrounding a galaxy to learn more about how it affects its evolution.
  • "There are these vast oceans of undetected gas that are just sort of lurking and surrounding star-forming galaxies, similar to our own Milky Way," Carlos Vargas, the leader of the Aspera mission, told me.
  • "Now is kind of the perfect time to start building things to observe in the far ultraviolet and ... this big undetected, unmapped reservoir of gas is just ripe for the taking right now," Vargas said.
  • The space telescope, funded by NASA, costs relatively little at $20 million, a price point that's only possible because manufacturing a telescope today is far cheaper than it used to be.

What's next: Scientists still haven't yet mapped exactly how gas expelled from galaxies moves through space and interacts with objects.

  • Researchers are also hoping to get more refined pictures of galaxies in the early universe in order to figure out exactly how they formed.
  • Future missions, like the James Webb Space Telescope, should help to shed light on possible answers to those problems in the coming years.
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