Ancient starburst galaxies that formed 2-3 billion years after the Big Bang are unusually hot and contain unexpected elements, like nickel, according to a new analysis of data collected by the CECILIA (Chemical Evolution Constrained using Ionized Lines in Interstellar Aurorae) survey.
In the Universe’s youth, many galaxies experienced a period of intense star formation.
Today, some galaxies, such as our own Milky Way, still form new stars, albeit not as rapidly. Other galaxies have stopped forming stars altogether.
This new work can help astronomers understand the reasons behind these different trajectories.
“We’re trying to understand how galaxies grew and changed over the 14 billion years of cosmic history,” said Dr. Allison Strom, an astronomer at Northwestern University.
“Using the NASA/ESA/CSA James Webb Space Telescope, our program targets ‘teenage’ galaxies when they were going through a messy time of growth spurts and change.”
Dr. Strom and colleagues studied the spectra from 33 distant galaxies, separating their light into its component wavelengths.
“We averaged together the spectra from all 33 galaxies to create the deepest spectrum of a distant galaxy ever seen — which it would take 600 hours of telescope time to replicate,” said Dr. Gwen Rudie, an astronomer at Carnegie Observatories.
“This enabled us to create an atlas, of sorts, that will inform future Webb observations of very distant objects.”
Using the spectra, the astronomers were able to identify eight distinct elements: hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon and nickel.
“These elements existing in these galaxies are not a surprise, but our ability to measure their light is unprecedented and shows the power of Webb,” Dr. Rudie said.
All elements that are heavier than hydrogen and helium form inside stars.
When stars explode in violent events like supernovae, they spew these elements out into the cosmic surroundings, where they are…
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