James Webb observes infancy and adolescence of galaxies – 12/01/2023 – Science

Since it came into operation last year, James Webb has made groundbreaking observations involving some of the first galaxies in the Universe — dubbed galactic babies.

But the telescope also obtained even better data on galaxies that are a little more advanced in their development, the galactic teenagers. And, as new research shows, they resemble human teenagers in certain ways, including the fact that they exhibit growth spurts along with a bit of immaturity.

The researchers focused on galaxies that formed about 2 billion to 3 billion years after the Big Bang, which 13.8 billion years ago began the Universe. They analyzed James Webb’s data on the light, emitted at different frequencies, from 23 galaxies — their “chemical DNA” — to trace the characteristics of the “teenagers”.

“These galaxies have unique chemical DNA, which indicates that they formed a considerable number of stars—already well developed—but are still growing rapidly,” said Allison Strom, professor of physics and astronomy at Northwestern University in Illinois, and author main study published on the 20th in the Astrophysical Journal Letters.

According to the researchers, they still do not look or behave like today’s galaxies.

“They go through some important processes at this time — many of which we don’t yet fully understand and hope to understand better soon — that define what kind of galaxy they will become,” said astronomer and study co-leader Gwen Rudie of the Carnegie Observatory in California.

The gas detected in star-forming regions —stellar nurseries— of teenage galaxies was much hotter, around 13,350°C, than that observed in today’s galaxies.

“The temperature in these parts of the galaxies is dominated by the young stars and the properties of the gas,” Strom said. “So finding a different temperature means there is something different about the stars and gas of teenage galaxies.”

Galaxies have been observed glowing with eight elements: hydrogen, helium, oxygen, nitrogen, sulfur, argon, nickel and silicon.

“Oxygen is notable because it is one of the most important components of ‘galactic DNA,’ in terms of tracking growth. Interestingly, oxygen is also the third most abundant element in the Universe [atrás do hidrogênio e do hélio]” said Strom.

“The level of nickel was surprising because, although we expected some amount to be present, it generally does not shine bright enough to be seen even in very nearby galaxies,” the professor continued. “So seeing it was a surprise and could indicate that there is something different about the massive stars that make the gas glow.”

Rudie said that there are probably more than these eight elements in these galaxies.

“Because elements heavier than hydrogen and helium are predominantly formed in stars, knowing what galaxies are made of tells us how many stars they formed in the past and how quickly they did so,” Strom said.

The findings, according to Strom, “point to a scenario in which these galaxies are still chemically ‘immature’ and are forming very quickly.”

Webb, which launched in 2021 and began collecting data last year, has reshaped understanding of the early Universe.

The new study presents the first results from the Cecilia Survey, which uses Webb to examine the chemistry of distant galaxies. The name Cecilia is an abbreviation for “Chemical Evolution Constrained using Ionized Lines in Interstellar Aurorae”, while also honoring the pioneering 20th century astronomer Cecilia Payne-Gaposchkin.

“There has rightly been a lot of excitement about how Webb has allowed us to see some of the first galaxies, but our ability to say much about these galaxies is limited,” Strom said. “At the same time, the telescope allows us to observe galaxies from a little later in the history of the Universe with an incredible amount of detail, and Cecilia is the first and, so far, the best example of this.”