Distant 'Teenage Galaxies' Surprise Astronomers with Unexpected Heavy Elements
Astronomers have been left baffled by the discovery of heavy elements in distant "teenage galaxies" that are far younger than previously thought possible. These galaxies, which formed just two to three billion years after the Big Bang, are unusually hot and contain elements like nickel, which are typically only produced by massive stars that explode as supernovae.
The findings, published in The Astrophysical Journal Letters, challenge our understanding of how galaxies evolve and could force scientists to rethink their models of star formation.
"We're trying to understand how galaxies grew and changed over the 14 billion years of cosmic history," said Allison Strom, an assistant professor of physics and astronomy at Northwestern University and lead author of the study. "This is a big step forward in that effort."
Strom and her team used the Keck Observatory in Hawaii to study the light from a cluster of distant galaxies known as the SSA22 group. By analyzing the spectrum of this light, they were able to identify the presence of eight different elements: hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon, and nickel.
The presence of nickel was particularly surprising, as it is a heavy element that is rarely seen in young galaxies. Nickel is produced when massive stars collapse and explode, releasing a burst of radiation that heats up the surrounding gas and dust. This process is thought to take billions of years to occur, so it was not expected to be seen in galaxies that are only a few billion years old.
"Never in my wildest dreams did I imagine we would see nickel," Strom said. "Even in nearby galaxies, people don't observe this."
The discovery of nickel in these teenage galaxies suggests that they may be forming stars at a much faster rate than previously thought. This could explain why they are so hot and why they contain such a large amount of heavy elements.
"These galaxies may be going through a period of rapid growth," Strom said. "They are forming stars very quickly, and this is producing a lot of heavy elements."
The new findings could have implications for our understanding of the early universe. If galaxies are forming stars much faster than we thought, then this could mean that the universe is filled with more stars than we currently believe.
"This could change our understanding of how the universe evolved," Strom said. "We may need to rethink our models of star formation."
Strom and her team are continuing to study the SSA22 galaxy cluster and other distant galaxies in order to learn more about how they formed and evolved. They are also planning to use the upcoming James Webb Space Telescope to study these galaxies in even more detail.
"The James Webb Space Telescope will allow us to see these galaxies in much more detail," Strom said. "We will be able to study their star formation rates and the composition of their gas and dust. This will help us to better understand how they formed and evolved."