Much like human youngsters, teenage galaxies are awkward, expertise progress spurts and luxuriate in heavy metallic — nickel, that’s.
A Northwestern College-led staff of astrophysicists has simply 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 House Telescope (JWST) to review the chemistry of distant galaxies.
In response to the early outcomes, so-called “teenage galaxies” — which shaped two-to-three billion years after the Massive Bang — are unusually scorching and comprise surprising components, like nickel, that are notoriously troublesome to watch.
The analysis can be printed on Monday (Nov. 20) in The Astrophysical Journal Letters. It marks the primary in a sequence of forthcoming research from the CECILIA Survey.
“We’re making an attempt to know how galaxies grew and altered over the 14 billion years of cosmic historical past,” mentioned Northwestern’s Allison Strom, who led the research. “Utilizing the JWST, our program targets teenage galaxies after they have been going by means of a messy time of progress spurts and alter. Youngsters typically 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 Middle 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 completely 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 “crimson and useless” whereas others, like our Milky Method, are nonetheless forming stars. A galaxy’s spectrum can reveal its key components, similar to oxygen and sulfur, which give a window into what a galaxy was beforehand doing and what it would do sooner or later.
“These teenage years are actually necessary as a result of that is when essentially the most progress occurs,” Strom mentioned. “By learning this, we are able to start exploring the physics that triggered the Milky Approach to appear to be the Milky Method — and why it would look completely different from its neighboring galaxies.”
Within the new research, Strom and her collaborators used the JWST to watch 33 distant teenaged galaxies for a steady 30 hours this previous summer season. 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.”
Spectra surprises
The ultra-deep spectrum revealed eight distinct components: Hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon and nickel. All components which might be heavier than hydrogen and helium kind inside stars. So, the presence of sure components gives details about star formation all through a galaxy’s evolution.
Whereas Strom anticipated to see lighter components, she was significantly stunned by the presence of nickel. Heavier than iron, nickel is uncommon and extremely troublesome to watch.
“By no means in my wildest desires 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 suitable circumstances to watch it. Nobody ever talks about observing nickel. Parts should be glowing in gasoline to ensure that us to see them. So, to ensure that us to see nickel, there could also be one thing distinctive in regards to the stars inside the galaxies.”
One other shock: The teenage galaxies have been extraordinarily scorching. By analyzing the spectra, physicists can calculate a galaxy’s temperature. Whereas the most popular pockets with galaxies can attain over 9,700 levels Celsius (17,492 levels Fahrenheit), the teenage galaxies clock in at greater than 13,350 levels Celsius (24,062 levels Fahrenheit).
“That is simply extra proof of how completely different galaxies possible have been after they have been youthful,” Strom mentioned. “In the end, the truth that we see the next attribute temperature is simply one other manifestation of their completely different chemical DNA as a result of the temperature and chemistry of gasoline in galaxies are intrinsically linked.”
The research, “CECILIA: Faint emission line spectrum of z~2-3 star-forming galaxies,” was supported by NASA, the Pittsburgh Basis and the Analysis Company for Scientific Development. The info have been obtained from the Mikulski Archive for House Telescopes on the House Telescope Science Institute and from the W.M. Keck Observatory.
