The James Webb Space Telescope (JWST) Advanced Deep Extragalactic Survey (JADES) is essentially a next-generation version of the Hubble Deep Field. But this latest look at the deep sky is on a different level, with 32 days of telescope work, infrared wavelengths that allowed JWST to see more distant galaxies than any previous telescope, and a much wider field of view than Hubble had.

Although the JADES program continues to collect data, team members Kevin Heinlein (Steward Observatory) and Ryan Endsley (University of Texas at Austin) announced the discovery of hundreds of ancient galaxies at a press conference at the 242nd meeting of the American Astronomical Society. . These galaxies reveal the chaotic state of the universe just hundreds of millions of years after the Big Bang.

REALLY EARLY GALAXIES

So far, the JADES team has identified 717 galaxies with a redshift greater than 8 when the universe was only 600 million years old. The most distant of these – “the farthest galaxy ever seen by humans” – has been spectroscopically confirmed to be at a redshift of 13, or just 200 million years after the Big Bang. If the entire history of the universe were a two-hour movie, then these galaxies allow us to observe scenes from the first two minutes to five minutes for the first time.

“This is important because we live in a complex universe, and the early universe consisted of hydrogen, helium, and light,” says Heinlein. “These are galaxies that started the process of creating the elements and complexity we see around us today.”

Before JWST, Hubble had seen two bright galaxies very early (redshift greater than 10). Currently, 93% of the galaxies JWST has collected are new and have never been identified before. “This,” Heinlein explains, “is the tip of the iceberg.”

The sample also provided an opportunity to calm down. Some in the community were concerned that not all of these so-called early galaxies were actually in the early universe. The astronomers first measured their distance using a method based on measuring their brightness in each of several color bands. Using this method, dusty, relatively close galaxies can mask more distant sources. But the JADES team dispelled that concern: Among the 42 galaxies the spectrum was studied, there were no masquerades from which astronomers could obtain more reliable redshift measurements.

HOW DID THAT HAPPEN?

Hundreds of galaxies offer a glimpse into the cosmos’s near-initial scenes, showing that things were different back then.

Endsley explains that about one-sixth of the first galaxies in the JADES sample are in a star formation stage that we have not seen in the near Universe, characterized by extremely bright emission at certain wavelengths. “Stars in very early galaxies form in these ultra-compact clusters,” he adds, “forming hundreds, perhaps thousands, of these very massive young stars all at once, often within a few million years.”

But they were not always “open”. The low rate of galaxies with this type of emission suggests that individual clusters will suddenly light up with new stars and then calm down for a while. This “explosive” way of star formation may explain the unexpectedly bright galaxies reported by other astronomers – they were just looking at galaxies that unexpectedly turned into intense star formation.

However, while these findings do explain ultra-bright galaxies, they do not explain extremely large galaxies, another controversial early finding from the JWST data. Endsley explains that even when hot, massive, newborn stars light up their galaxies, they don’t necessarily have to be associated with such a massive mass. “In fact, we find no evidence for these supermassive objects in our JADES sample,” he says.

There is much to learn from the JADES example as we continue with the JWST observations, such as a better understanding of the shape and size of galaxies.

Also, as the stars (and their associated dust) dominate the press conference, the central black holes of these galaxies await their turn to take center stage. “I think there are some really exciting examples of active supermassive black holes that people didn’t necessarily expect to exist in this very early period of the universe,” Endsley says. “This is something we really need to start thinking about as we move forward.”