Exploring the Cosmic Frontier: Key Discoveries from the James Webb Telescope

Melbourne:

Three years ago today, we experienced the thrilling launch of the James Webb Space Telescope (JWST), the largest and most advanced telescope humanity has ever dispatched into space.

Although it took 30 years to construct, in merely three brief years of operation, JWST has already transformed our perspective of the universe.

It has examined our own Solar System, analyzed the atmospheres of remote planets in search of signs of life, and delved into the farthest reaches to discover the very first stars and galaxies formed in the cosmos.

Here’s what JWST has revealed about the early universe since its launch – and the fresh enigmas it has brought to light.

Strange blue giants

JWST has extended the limits of how far we can observe the cosmos to discover the earliest stars and galaxies. With Earth’s atmosphere out of the equation, its positioning in space provides ideal conditions for looking into the vastness of the universe using infrared light.

The existing record for the most distant galaxy verified by JWST originates from a time when the universe was merely about 300 million years old. Surprisingly, within this brief period, this galaxy managed to develop approximately 400 million times the mass of our Sun.

This suggests that star formation in the early universe was exceptionally effective. And this galaxy is not unique.

As galaxies develop, their stars explode, generating dust. The larger the galaxy, the greater the amount of dust it possesses. This dust causes galaxies to present a red appearance as it absorbs blue light. But here’s the twist: JWST has demonstrated that these initial galaxies are astonishingly bright, massive and remarkably blue, with no indication of any dust. That presents a genuine conundrum.

Numerous theories exist to account for the strange characteristics of these initial galaxies. Do they possess colossal stars that collapse under gravity without undergoing massive supernova explosions?

Or do they experience such immense explosions that all dust is expelled far from the galaxy, revealing a blue, dust-free nucleus? Perhaps the dust is obliterated due to the extreme radiation from these early exotic stars – the truth remains unclear.

Uncommon chemistry in nascent galaxies

The early stars were essential components of what ultimately became life. The cosmos commenced with only hydrogen, helium, and a minimal amount of lithium. All other elements, from the calcium in our bones to the oxygen in the air we inhale, were produced in the hearts of these stars.

JWST has uncovered that early galaxies also display unusual chemical attributes.

They contain a substantial amount of nitrogen, significantly more than what we observe in our Sun, while most other metals are present in lower concentrations. This implies that there were mechanisms at play in the early universe that we do not yet fully comprehend.

JWST has indicated that our models of how stars drive the chemical progression of galaxies remain incomplete, signifying that we still do not fully grasp the circumstances that led to our existence.

Small entities that concluded the cosmic dark ages

Employing massive clusters of galaxies as enormous magnifying lenses, JWST’s sensitive sensors can also delve deep into thecosmos to identify the faintest galaxies.

We have progressed further to ascertain the threshold at which galaxies become so faint, they cease forming stars entirely. This assists us in understanding the circumstances under which galaxy formation concludes.

Though JWST has yet to determine this threshold, it has discovered numerous faint galaxies, significantly more than expected, releasing over four times the energetic photons (light particles) we forecasted.

This finding implies that these diminutive galaxies may have played a vital role in ending the cosmic “dark ages” not long after the Big Bang.

The enigmatic case of the small red dots

The initial images from JWST resulted in yet another astonishing, unforeseen find. The ancient universe brims with numerous “small red dots”: strikingly compact crimson sources of unknown origins.

At first, these were believed to be immense super-dense galaxies that defy possibility, yet extensive observations over the last year have revealed a mix of deeply perplexing and contradictory characteristics.

Luminous hydrogen gas emits light at astounding velocities, reaching thousands of kilometers per second, indicative of gas swirling around a supermassive black hole.

This occurrence, known as an active galactic nucleus, typically signifies a feeding frenzy where a supermassive black hole voraciously consumes all the surrounding gas, accelerating its growth.

However, these are anything but ordinary active galactic nuclei. For one, they emit no detectable X-rays, which is usually anticipated. Even more strikingly, they seem to possess the characteristics of star populations.

Could these galaxies represent both stars and active galactic nuclei simultaneously? Or are they at some transitional evolutionary stage? Regardless of their nature, these small red dots will likely impart knowledge about the origins of both supermassive black holes and stars in galaxies.

The astonishingly early galaxies

Besides extremely active early galaxies, JWST has also discovered extremely lifeless remnants: galaxies in the early universe that represent the remains of vigorous star formation during cosmic dawn.

These remnants had been detected by Hubble and ground-based telescopes, but only JWST possessed the capability to analyze their light and reveal how long they have been inactive.

It has unveiled some exceptionally massive galaxies (comparable to our Milky Way today and beyond) that emerged within the first 700 million years of cosmic history. Our current galaxy formation theories cannot account for these entities – they are excessively large and developed too soon.

Cosmologists continue to debate whether these models can be adjusted to fit (perhaps early star formation was remarkably efficient) or if we need to reconsider the essence of dark matter and how it leads to the formation of early collapsing structures.

JWST is poised to discover many more of these entities in the upcoming year and to examine the existing ones in greater depth. Regardless of the outcome, insights will be forthcoming.

What lies ahead for JWST?

The enigmatic red dots remained concealed from our perception. What else resides in the cosmic depths? JWST will soon provide answers.

(Authors:Themiya Nanayakkara, Researcher at the James Webb Australian Data Centre, Swinburne University of Technology; Ivo Labbe, ARC Future Fellow / Associate Professor, Swinburne University of Technology, and Karl Glazebrook, ARC Laureate Fellow & Distinguished Professor, Centre for Astrophysics & Supercomputing, Swinburne University of Technology)

(Disclosure Statement: Themiya Nanayakkara is awarded funding by the Australian Research Council Laureate Fellowship. Ivo Labbe is supported by the Australian Research Council through a Future Fellowship. Karl Glazebrook secures funding from the Australian Research Council for a Laureate Fellowship associated with JWST research and from the Australian Space Agency for training initiatives related to JWST)

This article is reprinted from The Conversation under a Creative Commons license. Access the original article.
 

(Aside from the headline, this story has not been modified by NDTV staff and is published from a syndicated source.)