From dead galaxies to mysterious red dots, here’s what the James Webb telescope discovered in just three years

Three years ago on this day, we witnessed the spectacular launch of the James Webb Space Telescope (JWST), the largest and most powerful telescope ever sent into space.

It took 30 years to build, but in just three years of operation, JWST has already revolutionized our view of the universe.

We’ve explored our own solar system, studied the atmospheres of distant planets for signs of life, and probed the deepest depths to find the first stars and galaxies to form in the universe.

Here, we discuss what JWST has taught us about the early Universe since its launch, and the new mysteries it has uncovered.

creepy blue monster

JWST pushed the boundaries of how far into the universe one could probe to find the first stars and galaxies. This location in space, unencumbered by Earth’s atmosphere, provides perfect conditions for peering into the depths of space in infrared light.

The current record of the most distant galaxies confirmed by JWST dates back to when the universe was only about 300 million years old. Remarkably, within this short time frame, this galaxy was able to form a mass approximately 400 million times that of our Sun.

This indicates that star formation in the early Universe was highly efficient, and not just in this galaxy.

As galaxies grow, stars explode and dust is created. The larger the galaxy, the more dust there will be. This dust absorbs blue light, making the galaxy appear red. But there’s a catch. JWST showed that these first galaxies were shockingly bright, massive, very blue, and without any sign of dust. It’s a real puzzle.

There are many theories that explain the strange properties of these first galaxies. Could there be a star so large that it simply collapses due to gravity without going into a massive supernova?

Or will there be an explosion so massive that all the dust will be pushed far away from the galaxy, exposing a dust-free blue core? Perhaps intense radiation from these early exotic stars will push the dust away? may have been destroyed, we don’t know yet.

Unusual chemistry of early galaxies

Early stars were important building blocks for what would eventually become life. The universe began with only hydrogen, helium, and a small amount of lithium. All other elements, from the calcium in our bones to the oxygen in the air we breathe, were forged in the cores of these stars.

JWST discovered that early galaxies also have unusual chemical signatures.

They contain significant amounts of nitrogen, much more than what we observe in the sun, but most other metals are present in smaller amounts. This suggests that processes that are not yet fully understood existed in the early universe.

JWST showed that our models of how stars drive the chemical evolution of galaxies are still incomplete. This means that we do not yet fully understand the conditions that led to our existence.

The small event that ended the dark ages of the universe

JWST’s sensitive camera can also use massive galaxy clusters as giant magnifying glasses to peer deep into the universe to find the faintest galaxies.

We continued our research and found the point at which the galaxy becomes so faint that star formation stops completely. This helps us understand the conditions under which galaxy formation ends.

JWST has not yet discovered this limitation. However, far more faint galaxies than expected were discovered, emitting more than four times as many high-energy photons (particles of light) as expected.

The discovery suggests that these small galaxies may have played an important role in ending the cosmic “Dark Ages” shortly after the Big Bang.

The mysterious incident of the little red dot

JWST’s first images yielded another dramatic and unexpected discovery. The early universe was rich in tiny red dots, very compact sources of red color of unknown origin.

Initially, they were thought to be gigantic, ultra-dense galaxies that should not exist, but detailed observations over the past year have revealed a very puzzling and contradictory combination of properties.

The bright hydrogen gas emits light at incredible speeds of thousands of kilometers per second, a characteristic of gas swirling around a supermassive black hole.

This phenomenon, called an active galactic nucleus, is typically indicative of a supermassive black hole swallowing up all the gas around it, in a rapidly growing feeding frenzy.

But these aren’t active galactic nuclei like the ones you have in your garden. First of all, it does not emit detectable X-rays, as one would normally expect. More interestingly, they appear to have the characteristics of a stellar population.

Are these galaxies simultaneously stars and active galactic nuclei, or are they at an evolutionary stage somewhere in between? Whatever it is, the little red dot probably tells us something about the birth of both supermassive black holes and stars in galaxies.

An impossibly early galaxy

JWST discovered extremely active early galaxies as well as extremely dead galaxies. This is a galaxy from the early universe, a remnant of intense star formation at the dawn of the universe.

These corpses had been discovered by Hubble and ground-based telescopes, but only the JWST had the power to analyze the light and reveal how much time had passed since death.

It discovered several extremely massive galaxies (as large or larger than today’s Milky Way) that formed during the first 700 million years of the universe’s history. Our current models of galaxy formation cannot explain these objects. They are too large and form too quickly.

Cosmologists are wondering whether they can bend their models to fit (for example, early star formation may have been very efficient) or whether they can change the nature of dark matter and how it We are still debating whether we need to reconsider what causes collapsing objects.

JWST plans to discover more of these objects and study existing ones in more detail next year. Either way, you’ll soon find out.

What’s next for JWST?

In its first stages, this telescope revealed many shortcomings in current models of the universe. While we are refining our model to take into account the updates that JWST brings, we are most excited about the unknown unknowns.

A mysterious red dot was hidden from our view. What else is left in the depths of the universe? JWST will let you know soon.

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