New Discoveries Shed Light on the Early Universe

New images captured by the James Webb Space Telescope (JWST) have played a crucial role in assisting Australian astronomers in unraveling the mysteries of how nascent galaxies initiated a surge of star formation during the earliest stages of the Universe.

In a recent study published today, astronomers have unveiled the existence of vibrant galaxies from approximately 12 billion years ago. These early galaxies were brimming with luminous gases that shone brighter than the nascent stars themselves.

Images captured by the James Webb Space Telescope (JWST) indicate that nearly 90% of the galaxies in the ancient universe exhibited this radiant gas, resulting in what is known as “extreme emission line features.”

The stars in these young galaxies were remarkable, producing just the right amount of radiation to excite the surrounding gas. This gas, in turn, shone even brighter than the stars themselves

Dr. Anshu Gupta, Lead Author, ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)

Dr. Anshu Gupta, also associated with the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), adds, “Until now, it was challenging to understand how these galaxies were able to accumulate so much gas. Our findings suggest that each of these galaxies had at least one close neighboring galaxy. The interaction between these galaxies would cause gas to cool and trigger an intense episode of star formation, resulting in this extreme emission feature.”

The finding is a graphic example of the unrivaled clarity the JWST telescope provides in studying the early Universe.

“The data quality from the James Webb telescope is exceptional,” says Dr. Gupta. “It has the depth and resolution needed to see the neighbors and environment around early galaxies from when the Universe was only 2 billion years old. With this detail, we were able to see a marked difference in the number of neighbors between galaxies with the extreme emission features and those without.”

In the past, obtaining a clear view of galaxies dating back to roughly 2 billion years after the birth of the Universe proved challenging. The scarcity of fully formed stars compounded the difficulty, as there were significantly fewer galaxies available for observation.

Dr. Gupta adds, “Prior to JWST, we could only really get a picture of really massive galaxies, most of which are in really dense clusters making them harder to study. With the technology available then, we couldn’t observe 95% of the galaxies we used in this study. The James Webb telescope has revolutionized our work.”

According to fellow author Associate Director Tran, ASTRO 3D and the Center of Astrophysics, Harvard and Smithsonian, the discovery has proven previous assumptions. “We suspected that these extreme galaxies are signposts of intense interactions in the early universe, but only with the sharp eyes of JWST could we confirm our hunch.”

This research drew upon data collected as part of the JWST Advanced Deep Extragalactic Survey (JADES), a survey dedicated to delving into the Universe's earliest galaxies through deep infrared imaging and multi-object spectroscopy. This data provides a gateway to uncovering more profound insights into these ancient celestial structures.

“What’s really exciting about this piece is that we see emission line similarities between the very first galaxies to galaxies that formed more recently and are easier to measure. This means we now have more ways to answer questions about the early universe, a period that is technically very hard to study,” notes Ravi Jaiswar, second author and PhD Student, Curtin University/ICRAR and ASTRO 3D.

This research is core to the work of our Galaxy Evolution Program. By understanding what early galaxies look like, we can build on answering questions on the origin of the elements that make up our everything in our everyday life here on Earth.

Emma Ryan-Weber, Professor and Director, ASTRO 3D