The deeper we look into space, the further into time we see. Light emanating from some of the youngest galaxies in our universe must travel billions of years to reach us, and is captured by our instruments, rich in information from the cosmic dawn. And not only can this light tell us where we come from, but also where we might be going.
To understand the evolution of several of these “teenage” galaxies in the early universe, a team of astrophysicists led by Northwestern University inspected data from the James Webb Space Telescope (JWST), which observed realms that do not formed only two to three billion years after the Big Bang.
The sightings held some intriguing surprises.
Specifically, the team analyzed results from the CECILIA (Chemical Evolution Constrained using Ionized Lines in Interstellar Aurorae) survey to find that not only do these galaxies appear hotter than expected, but they also appear to host heavy elements, like nickel.
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The researchers focused on 33 distant galaxies for a continuous 30-hour period. They then combined the wavelengths of light collected from 23 of these galaxies to create a composite picture of what’s happening in these structures. These spectra contain clues about things like their average temperatures and what elements might be hiding there.
“This erases the details of individual galaxies but gives us a better idea of an average galaxy. It also allows us to see fainter features,” said Allison Strom, lead author of the study and assistant professor of physics and science. astronomy at Northwestern University. in a report.
The composite image of galaxies contained eight identifiable elements: hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon and nickel. While we expected lighter elements, the presence of nickel, heavier than iron in the periodic table, was somewhat surprising.
“Never in my wildest dreams did I imagine we would see nickel,” Strom said.
Even in older, nearby galaxies, nickel is rarely observed – and that’s after several star life cycles, which means multiple rounds of supernovas and the chance for heavier elements to synthesize and spread throughout the galaxy. galaxy.
“No one ever talks about observing nickel. The elements have to glow in the gas for us to see them. So for us to see nickel, there may be something unique in the stars of galaxies” , Strom said.
Strom thinks that the higher temperatures observed in these early galaxies might be somehow related to their curious chemical composition: “Ultimately, the fact that we observe a higher characteristic temperature is just that. “another manifestation of their different chemical DNA, as temperature and gas chemistry in galaxies are intrinsically linked.”
The study was published November 20 in The Astrophysical Journal Letters.