Looking deeper into space reveals the past; and light from young galaxies, traveling for billions of years, carries cosmic dawn's information.
Northwestern University astrophysicists used James webb Space Telescope (JWST) to analyze Chemical Evolution Constrained using Ionized Lines in Interstellar Aurorae (CECILIA) Survey's early findings, exploring the chemistry of distant galaxies and revealing surprising details about "teenage" galaxies formed 2-3 billion years after the Big Bang.
Decoding Galactic 'DNA' with JWST
The CECILIA Survey, honoring Cecilia Payne-Gaposchkin, a trailblazing astronomer, investigates spectra from distant galaxies, treating a galaxy's spectra as its "chemical DNA."
This approach, likened to studying a galaxy's adolescence, provides insights into its growth and future evolution. By examining this 'chemical DNA' during a galaxy's formative "teenage" years, researchers aim to unravel the mysteries of its development.
Astronomers grapple with the enigma of why certain galaxies, like the Milky Way, are actively forming stars, while others appear "red and dead." A galaxy's spectrum, unveiling elemental composition like oxygen and sulfur, serves as a key to deciphering its past activities and future trajectory.
The teenage years are pivotal in a galaxy's lifecycle, representing a period of significant growth. Studying this phase allows researchers to delve into the underlying physics that shaped galaxies like the Milky Way and understand why they differ from neighboring counterparts.
In a recent study, titled "CECILIA: The Faint Emission Line Spectrum of z ∼ 2-3 Star-forming Galaxies" published in The Astrophysical Journal Letters, Allison Strom and her team utilized JWST to observe 33 distant teenage galaxies continuously for 30 hours.
By combining spectra from 23 of these galaxies, they created a composite image. While sacrificing the details of individual galaxies, this method provided a clearer picture of an average galaxy and revealed fainter features.
The depth and precision achieved with JWST surpassed the capabilities of ground-based telescopes, offering a more comprehensive understanding of galaxies during this crucial epoch in the universe's history.
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Nickel's Unusual Presence in Early Galaxies Challenges Galactic Norms
Analyzing the spectra, astronomers identified eight distinct elements within the observed galaxies: hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon, and unexpectedly, nickel, a heavier element than iron in the periodic table.
The presence of nickel, particularly in early galaxies, proved surprising, as it is rarely observed even in older galaxies nearby. In typical galactic life cycles, multiple rounds of supernovas occur, providing opportunities for heavier elements to synthesize and disperse throughout the galaxy. Nickel's scarcity in observations raises questions about the unique stellar characteristics within these early galaxies.
The unexpected discovery of nickel holds significance, considering that even in mature galaxies with multiple stellar life cycles, nickel is seldom observed. Strom emphasizes that elements must emit light in gas for observation, and the observation of nickel suggests distinctive properties in the stars of these galaxies.
Overall, the identification of nickel in the spectra of early galaxies challenges conventional expectations, hinting at distinctive stellar characteristics and raising questions about the interconnectedness of temperature and chemical composition in shaping the galaxies' unique attributes.
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