Galaxies Grow Up in the JWST’s Deepest Look Into Cosmic Noon

There are moments in science when a new tool doesn’t just refine what we already know—it revolutionizes it. The James Webb Space Telescope (JWST) is that kind of tool. Now, thanks to the MEGA (MIRI EGS Galaxy and AGN) survey led by the University of Kansas, we’re seeing a part of the cosmos that has never been visible before. This is not just a step forward—it’s an interstellar leap.

The MEGA survey targets one of the most intriguing periods in the universe’s 13.8-billion-year history: cosmic noon. This era, occurring 2–3 billion years after the Big Bang (roughly 10 to 11 billion years ago), was the universe’s most vigorous growth spurt. Galaxies then were prolific star factories and home to rapidly evolving supermassive black holes. Until now, most of this activity was hidden behind veils of cosmic dust. But in the mid-infrared spectrum—JWST’s specialty—dust becomes transparent, and the story of the adolescent universe is suddenly laid bare.

The MEGA survey is the largest mid-infrared extragalactic survey conducted to date. Its revelations are poised to transform our understanding of how galaxies like the Milky Way came into being, matured, and shaped the cosmic landscape.

A Mission Into the Murky Past

The goal of the MEGA survey is audacious: to untangle the story of galaxy evolution by investigating how galaxies formed their stars and grew their central black holes during the most energetic period in cosmic history.

“All galaxies today owe half of their stellar mass to stars forged during cosmic noon,” said Dr. Allison Kirkpatrick, principal investigator of the MEGA survey and associate professor of physics and astronomy at KU. “We want to understand what drove that explosive growth—especially in dusty galaxies that were previously invisible in other wavelengths.”

Why mid-infrared? In visible light, many of these galaxies are opaque. Dust, abundant in star-forming regions, blocks or scatters light, making them hard to observe. But in the mid-infrared range, dust actually glows, revealing the bustling activity hidden within. That makes JWST’s MIRI (Mid-Infrared Instrument) a perfect lens for this cosmic autopsy.

The MEGA survey zeroes in on a part of the sky known as the Extended Groth Strip, located near the Ursa Major constellation. This small patch—only about the width of the moon in the night sky—has been deeply studied in the past, but never with JWST’s mid-infrared eyes. What astronomers are finding there now is nothing short of astonishing.

Inside the Extended Groth Strip: A Cosmic Treasure Chest

The Extended Groth Strip (EGS) has long been a favorite target for astronomers. It’s a quiet patch of sky, free from the interference of our own galaxy, and thus a clean window into the distant universe. What makes it especially exciting today is that it was one of the first regions imaged by JWST, under a program called CEERS (Cosmic Evolution Early Release Science).

“When we first got the CEERS data from JWST, we were shocked by what we saw,” Kirkpatrick said. “This tiny sliver of sky contained more than 10,000 galaxies.”

Some of these galaxies are over 13 billion years old. Light from them began traveling long before Earth even existed. Others are just a few billion years old, sitting squarely in the cosmic noon window. By capturing their light in the mid-infrared, astronomers can now dissect their structures, measure their star formation rates, estimate black hole growth, and look for signs of mergers and interactions.

This is not just data collection—it’s storytelling. Each galaxy is a character, each supermassive black hole a mysterious force of transformation, each dust cloud a veil over a cosmic drama. And the MEGA survey is peeling back those veils, one photon at a time.

Behind the Scenes: Making the Data Come to Life

The journey from JWST’s observations to usable scientific insights is neither fast nor simple. Dr. Bren Backhaus, a postdoctoral researcher at KU and the survey’s lead data processor, played a crucial role in converting raw telescope data into usable images and catalogs.

“In theory, a galaxy could show up in one filter but be invisible in another,” Backhaus explained. “That’s like photographing the same scene with red, blue, and green filters—it gives us a lot of information, but it has to be stitched together with extreme precision.”

Every JWST image contains distortions and artifacts—scratches from the optics, dead pixels in the detectors, even slight motion between exposures. Backhaus’s job was to align, correct, and clean this visual cacophony, turning it into science-ready data.

“I got to see some of these galaxies before anyone else,” she said. “It was magical—like opening a window into the ancient universe.”

Once aligned and corrected, the images are analyzed for photometry—measuring how much light each object emits in each filter. That light, when interpreted properly, tells astronomers the age, mass, and star formation rate of the galaxy, and even how much material is falling into its central black hole.

Dusty Starbirths and Hungry Black Holes

So what exactly is JWST revealing through this survey?

First, there’s an astonishing level of star formation. Some galaxies were creating stars at hundreds of times the rate of today’s Milky Way. This hyperactivity appears linked to interactions between galaxies—gravitational dances that stir up gas, compress it, and ignite rapid star formation.

Secondly, black holes in these galaxies aren’t sleeping giants—they’re ravenous monsters. Many of the observed galaxies house active galactic nuclei (AGN), which are black holes consuming vast amounts of matter and glowing brilliantly in the process.

“Black hole growth and star formation often go hand in hand,” said Kirkpatrick. “We want to understand if one triggers the other, or if they’re both just feeding off the same influx of gas.”

The mid-infrared images show not just the presence of AGN, but also how their energy interacts with surrounding matter—sometimes triggering new starbursts, other times halting star formation by heating or expelling gas.

Cosmic Collisions: Galaxies in Motion

Another key goal of the MEGA survey is to identify and analyze galactic mergers—collisions between galaxies that profoundly affect their evolution. These cosmic smash-ups were more common during cosmic noon and may have driven much of the star and black hole growth seen at the time.

To accelerate this research, the MEGA team is turning to the public. Through the Cosmic Collisions Zooniverse project, volunteers can examine JWST images and help classify galaxy shapes and look for signs of merging. This “citizen science” effort brings the public into the discovery process, allowing anyone with curiosity and a few spare minutes to participate in cutting-edge research.

“We’re asking people to help us recognize the signs of galactic interactions,” said Kirkpatrick. “It’s like a giant interstellar game of ‘spot the difference’—but the stakes are real science.”

From Kansas to the Cosmos

The University of Kansas is now at the epicenter of this cosmic investigation. MEGA is the largest JWST survey ever led by KU, with 67 hours of observing time already logged and 30 more awarded for the near future. For now, KU researchers and students have exclusive access to this treasure trove of mid-infrared data—a rare privilege in the fiercely competitive world of space telescopes.

“This is a unique moment for KU,” Kirkpatrick said. “My students are working on every aspect of this data—from analyzing AGN to identifying galaxy shapes. It’s an incredible opportunity for hands-on research.”

As per telescope policy, the data will eventually be made public, but only after the initial one-year period of exclusive access. Even then, it will be in raw form—meaning researchers elsewhere will have to process it themselves, a task that took months for the MEGA team.

Tracing the Ancestors of the Milky Way

One of the most tantalizing aspects of the MEGA survey is its potential to reveal the ancestors of galaxies like our own. For the first time, astronomers can see galaxies at a stage of development when they might resemble the early Milky Way—bursting with star formation, rich in gas and dust, and growing their central black holes.

By identifying these precursor galaxies and measuring their properties, researchers can build models of how disk galaxies, spiral arms, and large-scale structure emerged over billions of years.

“We’re literally watching galaxies grow up,” said Kirkpatrick. “It’s like having a photo album of the universe’s teenage years.”

A New Chapter in Cosmic Evolution

The MEGA survey is just the beginning. As JWST continues to scan the universe in unprecedented detail, more surveys like this will follow. But MEGA has already established a gold standard—not just for what we can learn, but how we can learn it.

The combination of advanced instrumentation, sophisticated data processing, and public engagement has created a model of 21st-century astronomy: one that is open, collaborative, and deeply curious about our origins.

“We’re at a turning point,” said Backhaus. “With JWST and MEGA, we’re not just adding details to existing theories—we’re rewriting the story of how the universe evolved.”

From dusty star nurseries to feeding black holes, from colliding galaxies to cosmic adolescence, the MEGA survey is peeling back time itself. The cosmos has never looked so alive—or so human.

Reference: Bren E. Backhaus et al, MEGA Mass Assembly with JWST: The MIRI EGS Galaxy and AGN Survey, arXiv (2025). DOI: 10.48550/arxiv.2503.19078