Webb Reveals Milky Way’s Ancient Twin Sparkling From the Cosmic Dawn

NASA’s James Webb Space Telescope has uncovered the Firefly Sparkle galaxy, a young cosmic entity that may resemble the Milky Way in its infancy.

This discovery, made possible by Webb’s incredible resolution and gravitational lensing, reveals 10 dazzling star clusters that could eventually evolve into globular clusters. The study provides a critical glimpse into galaxy formation, suggesting that galaxies grow both internally and through collisions.

A Glimpse into the Early Universe

NASA’s James Webb Space Telescope has detected and measured the mass of a distant galaxy that existed just 600 million years after the Big Bang. This newly identified galaxy, called Firefly Sparkle, may resemble what the Milky Way looked like in its earliest stages of formation.

Firefly Sparkle is dotted with ten bright star clusters, which could provide clues about how early galaxies formed. Scientists believe that galaxies may have started as fragmented clusters of stars, some of which evolved into the globular clusters we see today.

The findings, published in Nature, were led by former Dunlap Institute postdoctoral fellows Lamiya Mowla and Kartheik Iyer. Mowla is now an assistant professor at Wellesley College in Massachusetts, while Iyer is a NASA Hubble Fellow at Columbia University in New York.

Also contributing to the research is Roberto Abraham, professor and chair of the David A. Dunlap Department of Astronomy & Astrophysics at the University of Toronto. He is part of the Canadian NIRISS Unbiased Cluster Survey (CANUCS) team, which played a key role in this discovery. In an interview with A&S News, Abraham shared insights into what this finding reveals about the universe’s earliest galaxies:

By turning its eye on the Firefly Sparkle galaxy, how is Webb helping us understand things about the universe that we didn’t know before?

Webb’s resolution and sensitivity allows us to study extremely distant objects — like those gleaming star clusters that initially drew us to the Firefly Sparkle galaxy — in crisp detail. We’re also able to “zoom in” due to a natural effect known as strong gravitational lensing. In this case, a galaxy cluster in the foreground enhanced the Firefly Sparkle galaxy behind it, acting like a giant magnifying glass.

With Webb, we can go back in time and look at distant objects like the Firefly Sparkle and see objects in it that may be young globular clusters, which are seen today as dense groups of millions of ancient stars. Witnessing things that are ancient today being born in the distant past is mind-blowing. Seeing 10 of them forming this way makes the Firefly Sparkle a goldmine for understanding the earliest phases of formation and growth in galaxies.

Using Webb’s images and data, the researchers concluded that the Firefly Sparkle had the same mass as our Milky Way galaxy would have if we could “turn back time” to weigh it as it was assembling. Why is knowing the “weight” of the Firefly Sparkle galaxy important?

It gives us a glimpse of how much young galaxies weighed when the universe was very young. Today’s galaxies are way more massive. We’ve known this for a while, but Webb lets us figure out how they get more massive, and how they get so many stars within them. In some models, the stars form slowly via internal processes, while in other models they form in small galaxies which crash together and grow bigger. Galaxies like the Firefly Sparkler tell us that both things are happening, but the latter process is probably dominant.

In 2022, the CANUCS team used Webb to identify the most distant globular clusters known, in what they dubbed “the Sparkler galaxy.” How does this new discovery build upon the previous one?

The little points of light — “sparkles” — seen in the Sparkler galaxy we studied in 2022 were four billion years old when their light was emitted, which was similar to the age of the universe then. Nine billion years later, in today’s universe, we know exactly what they look like: today’s globular clusters. With the new Firefly Sparkle galaxy, we’re closer to the starting point of growth, so we’re not 100 percent sure what the little points of light in the galaxy evolve into.

You could say that looking at the Sparkler galaxy was like looking at a toddler: you’re pretty sure a toddler is going to eventually grow up to look like an adult. But with Firefly Sparkle, it’s like looking at an embryo: all sorts of animals have similar-looking embryos, so in this case what those sparkles turn into is more ambiguous.

What are you excited to look for next with Webb?

It’s more like, what am I not excited to look at next with Webb? All the data and images coming from Webb fill me with a sense of giddy joy — it feels a bit like the universe is letting us in on some pretty big secrets and we’re lucky to be alive right now.

In this case, we need to find more examples of systems similar to the Sparkler and the Firefly Sparkle to be totally confident that these little points of light in the Firefly Sparkle are indeed very young globular clusters. What we’ve got now is a spectacular starting point! Canada has a long history of galaxy formation and globular cluster research, so I look forward to seeing us continue along that path.

Explore Further:

• Webb Reveals Milky Way’s Ancient Twin Sparkling From the Cosmic Dawn
• Stunning James Webb Images Reveal the Birth of a Milky Way Twin

Reference: “Formation of a low-mass galaxy from star clusters in a 600-million-year-old Universe” by Lamiya Mowla, Kartheik Iyer, Yoshihisa Asada, Guillaume Desprez, Vivian Yun Yan Tan, Nicholas Martis, Ghassan Sarrouh, Victoria Strait, Roberto Abraham, Maruša Bradač, Gabriel Brammer, Adam Muzzin, Camilla Pacifici, Swara Ravindranath, Marcin Sawicki, Chris Willott, Vince Estrada-Carpenter, Nusrath Jahan, Gaël Noirot, Jasleen Matharu, Gregor Rihtaršič and Johannes Zabl, 11 December 2024, Nature.
DOI: 10.1038/s41586-024-08293-0

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