‘Teenage galaxies’ are unusually hot, glowing with unexpected elements

Much like human youngsters, teenage galaxies are awkward, expertise development spurts and revel in heavy metallic—nickel, that’s.

A Northwestern College-led workforce of astrophysicists has analyzed the primary outcomes from the CECILIA (Chemical Evolution Constrained using Ionized Lines 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 line with 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 tough 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 sequence of forthcoming research from the CECILIA Survey.

“We’re attempting to grasp how galaxies grew and adjusted 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 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 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 ladies 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 inspecting 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 Way, are nonetheless forming stars. A galaxy’s spectrum can reveal its key parts, resembling oxygen and sulfur, which give 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 brought about the Milky Way to seem like the Milky Way—and why it’d look totally different from its neighboring galaxies.”

Within the new research, Strom and her collaborators used the JWST to look at 33 distant teenage 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 may 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 parts: Hydrogen, helium, nitrogen, oxygen, silicon, sulfur, argon and nickel. All parts which are heavier than hydrogen and helium type inside stars. So, the presence of sure parts offers 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 tough to look at.

“By no means in my wildest desires did I think about we’d see nickel,” Strom mentioned. “Even in close by galaxies, individuals do not observe this. There needs to be sufficient of a component current in a galaxy and the appropriate situations to look at it. Nobody ever talks about observing nickel. Components must 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 throughout the galaxies.”

One other shock: The teenage galaxies have been extraordinarily sizzling. By inspecting the spectra, physicists can calculate a galaxy’s temperature. Whereas the most popular 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 extra proof of how totally different galaxies doubtless have been after they have been youthful,” Strom mentioned. “Finally, the truth that we see the next 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 research knowledge have been obtained from the Mikulski Archive for House Telescopes on the House Telescope Science Institute and from the W.M. Keck Observatory.