‘The universe will get colder and deader from now on’: Euclid telescope confirms star formation has already peaked in the cosmos
A telescope tasked with drawing the largest map of the universe ever made has confirmed a hard, if unsurprising, truth: Nothing lasts forever, not cold November rainor even the cosmos itself.
Using an extensive catalog of observations from the European Space Agency (ESA) Euclid and the Herschel Space Telescopes, a team of 175 researchers made the most complete reading of the temperature of the universe ever recorded. By studying the heat emitted by stardust in more than 2 million galaxies, the team found that galaxies have cooled slightly and star formation rates have slowed over the last 10 billion years of cosmic history.
These slight but clear downward trends suggest that the universe’s days of peak growth are over, researchers say. While the expiration date of the cosmos is still a mind-boggling amount of time away (somewhere between 33 billion And 1 quinvigintillion years – that’s 1 followed by 78 zeros – according to recent estimates), the new findings suggest that in terms of star formation rates, it’s all downhill from here.
A 3D map of the universe
In March, ESA’s recently activated Euclid telescope shared its first large publication of dataincluding observations of 26 million galaxies spanning over 10.5 billion light years in cosmic distance. It was just the first phase of the telescope’s mission to build the largest-ever 3D map of the universe, with the ultimate goal of mapping about 1.5 billion galaxies covering a third of the night sky.
For their new study, the researchers looked at 2.6 million galaxies cataloged in the first Euclid data release and combined them with archival observations from ESA’s Herschel Space Observatory, active from 2009 to 2013). While Euclid’s pair of onboard instruments are tuned to record visible and near-infrared light, Herschel’s instruments detected far-infrared light. Therefore, combining these datasets allowed the team to study the heat emitted by stardust over a wide range of wavelengths, providing the most comprehensive measurements of galactic temperatures ever taken.
“By combining the data and having such a large sample of galaxies… we can produce the most statistically robust calculations to date,” said the study’s lead author. Ryley Hillpostdoctoral researcher at UBC, said in the release.
The team found that the average temperature of galaxies has cooled only slightly over the past 10 billion years, falling by just 10 kelvins. While the stars love the sun blaze more than a million kelvinsGalaxies are mostly empty space, which means their average temperatures are much lower. The average galactic temperature of the first galaxies observed in the new study was about 35 K (minus 396 F or minus 238 C), the researchers found.
It’s a small change, but the heat from stardust is directly linked to star formation, the team noted. Hotter galaxies tend to have higher star formation rates because they contain greater numbers of hot, massive stars. Likewise, galaxies with less star formation tend to be cooler on average. The team’s research confirms this correlation and proves that star formation is slowly declining across the cosmos.
From dust to dust
It may be a chore to deal with on Earth, but dust is essential to the life cycle of stars. Stars form when clouds of gas and dust become so dense that they collapse under their own gravity, heating and rotating in the process. If one of these collapsed clusters becomes hot and dense enough, nuclear fusion triggers in its core, forming a star. Eventually, when the star exhausts its nuclear fuel reserves billions of years later, it will explode as a supernova, spewing even more dust into its vicinity and allowing the next generation of stars to develop.
Galaxies can lack star-forming material in several ways; they may be cut off from their gas supply during galaxy mergers, or have their star-forming material violently expelled into space by supermassive ships. black hole explosions, just to name a few. Eventually, a galaxy lacking enough star-forming material becomes extinct – starved for fuel and doomed to become extinct.
The new results suggest that our universe is on track to be completely extinct – but, again, not for an unfathomably long time. Earth’s sun will run out of fuel and explode long before the Milky Way dries up, and more massive objects like black holes will live for many eons after that. Meanwhile, the new research offers the most precise investigation yet of some of the key conditions of galaxies across the universe – measurements that will be essential in Euclid’s quest to build the ultimate map of our cosmos.
