Just like human youngsters, teenage galaxies are awkward, expertise development spurts and revel in heavy steel—nickel, that’s.
A Northwestern College-led crew of astrophysicists has analyzed the primary outcomes from the CECILIA (Chemical Evolution Constrained utilizing Ionized Traces in Interstellar Aurorae) Survey, a program that makes use of NASA’s James Webb Area Telescope (JWST) to check the chemistry of distant galaxies.
In response to the early outcomes, so-called “teenage galaxies”—which fashioned two-to-three billion years after the Massive Bang—are unusually sizzling and include sudden parts, like nickel, that are notoriously troublesome to look at.
The analysis, “CECILIA: Faint emission line spectrum of z~2-3 star-forming galaxies,” was revealed on Nov. 20 in The Astrophysical Journal Letters. It marks the primary in a collection of forthcoming research from the CECILIA Survey.
“We’re attempting to know how galaxies grew and altered over the 14 billion years of cosmic historical past,” mentioned Northwestern’s Allison Strom, who led the examine. “Utilizing the JWST, our program targets teenage galaxies after they have been going via a messy time of development spurts and alter. Youngsters usually have experiences that decide their trajectories into maturity. For galaxies, it is the identical.”
One of many principal investigators of the CECILIA Survey, Strom is an assistant professor of physics and astronomy at Northwestern’s Weinberg Faculty of Arts and Sciences and a member of Northwestern’s Heart for Interdisciplinary Exploration and Analysis in Astrophysics (CIERA). Strom co-leads the CECILIA Survey with Gwen Rudie, a workers scientist at Carnegie Observatories.
‘Chemical DNA’ offers perception into galaxy formation
Named after Cecilia Payne-Gaposchkin, one of many first girls to earn a Ph.D. in astronomy, the CECILIA Survey observes spectra (or the quantity of sunshine throughout totally different wavelengths) from distant galaxies. Strom likens a galaxy’s spectra to its “chemical DNA.” By analyzing this DNA throughout a galaxy’s “teenage” years, researchers can higher perceive the way it grew and the way it will evolve right into a extra mature galaxy.
For instance, astrophysicists nonetheless do not perceive why some galaxies seem “pink and useless” whereas others, like our Milky Manner, are nonetheless forming stars. A galaxy’s spectrum can reveal its key parts, comparable to oxygen and sulfur, which offer a window into what a galaxy was beforehand doing and what it’d do sooner or later.
“These teenage years are actually essential as a result of that is when probably the most development occurs,” Strom mentioned. “By finding out this, we will start exploring the physics that prompted the Milky Strategy to appear like the Milky Manner—and why it’d look totally different from its neighboring galaxies.”
Within the new examine, Strom and her collaborators used the JWST to look at 33 distant teenage galaxies for a steady 30 hours this previous summer time. Then, they mixed spectra from 23 of these galaxies to assemble a composite image.
“This washes out the small print of particular person galaxies however offers us a greater sense of a mean galaxy. It additionally permits us to see fainter options,” Strom mentioned. “It is considerably deeper and extra detailed than any spectrum we might accumulate with ground-based telescopes of galaxies from this time interval within the universe’s historical past.”
The ultra-deep spectrum revealed eight distinct parts: Hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon and nickel. All parts which might be heavier than hydrogen and helium kind inside stars. So, the presence of sure parts gives details about star formation all through a galaxy’s evolution.
Whereas Strom anticipated to see lighter parts, she was notably stunned by the presence of nickel. Heavier than iron, nickel is uncommon and extremely troublesome to look at.
“By no means in my wildest goals did I think about we’d see nickel,” Strom mentioned. “Even in close by galaxies, folks do not observe this. There must be sufficient of a component current in a galaxy and the appropriate situations to look at it. Nobody ever talks about observing nickel. Components should be glowing in fuel to ensure that us to see them. So, to ensure that us to see nickel, there could also be one thing distinctive concerning the stars inside the galaxies.”
One other shock: The teenage galaxies have been extraordinarily sizzling. By analyzing the spectra, physicists can calculate a galaxy’s temperature. Whereas the most well liked pockets with galaxies can attain over 9,700° Celsius (17,492° Fahrenheit), the teenage galaxies clock in at greater than 13,350° Celsius (24,062° Fahrenheit).
“That is simply further proof of how totally different galaxies doubtless have been after they have been youthful,” Strom mentioned. “In the end, the truth that we see a better attribute temperature is simply one other manifestation of their totally different chemical DNA as a result of the temperature and chemistry of fuel in galaxies are intrinsically linked.”
The examine information have been obtained from the Mikulski Archive for Area Telescopes on the Area Telescope Science Institute and from the W.M. Keck Observatory.
Allison L. Strom et al, CECILIA: Faint emission line spectrum of z~2-3 star-forming galaxies, The Astrophysical Journal Letters (2023). On arXiv: DOI: 10.48550/arxiv.2308.13508
‘Teenage galaxies’ are unusually sizzling, glowing with sudden parts (2023, November 20)
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