They discovered an ancient source of light that lit up the entire universe – Teach me about science

One of the biggest mysteries we have been trying to decipher for hundreds of years concerns the origin of our universe. After understanding that our planet is part of the solar system and that this in turn is part of the Milky Way galaxy, scientists began to investigate the existence of other galaxies and discovered the expansion of the universe. In this way, they were able to calculate the age of the universe and began to develop theories about its possible origin.

Today we’re taking a look at one of the biggest discoveries in astronomy, in which researchers believe they’ve tracked down an ancient light source that could be responsible for “powering the entire universe.”

Hundreds of years old mystery

For centuries, scientists and philosophers have been fascinated by theories about the origin of the universe. One of the most mysterious stages in cosmic timelines is the Epoch of Reionization, a crucial period that occurred about a billion years after the Big Bang. During this era, the first photons emitted by galaxies began to transform the universe into the vast and complex cosmos we see today.

A new study by an international team of scientists has identified dwarf galaxies dating back more than a billion years as the source of the first photons that ignited cosmic reionization. The findings, published in the journal Nature, were achieved by analyzing data from the $10 billion James Webb Space Telescope (JWST). The research was conducted as part of the UNCOVER (Ultradeep NIRSpec and NIRCam Observations Before the Epoch of Reionization) program, which uses a suite of advanced techniques to study these extremely faint galaxies.

According to the explanation provided by astronomer Hakim Atiq of the Sorbonne University, who led the study:

“NIRSpec’s incredible sensitivity, combined with the gravitational amplification provided by Abell 2744, allowed us to identify and study these galaxies in detail.”

Advanced technology has allowed scientists to observe the universe in unprecedented detail. The findings provide a new window into the era of reionization, helping to better understand the processes that shaped the universe’s first billion years. Abell 2744, also known as the Pandora cluster, made this observation possible because of the gravitational lensing effect, which uses the curvature of spacetime around massive objects as a lens. The cluster, a combination of at least four smaller galaxy clusters, allowed scientists to detect light sources from eight extremely faint galaxies.

“This discovery reveals the crucial role played by very faint galaxies in the early evolution of the Universe,” said Irena Chemerinska, an astrophysicist at the Institut de l’Astrophysique de Paris and co-author of the study. “They produce ionizing photons that transform neutral hydrogen into ionized plasma during cosmic reionization.”

This discovery is a major achievement given the difficulty of detecting these galaxies. To achieve this, the researchers used advanced technology such as JWST’s Near-Infrared Camera (NIRCam) and Near-Infrared Spectrometer (NIRSpec).

Discovering extremely faint galaxies

The team used NIRSpec’s Multiple Shutter Montage technique, which allowed them to capture multi-object spectroscopy of these extremely faint galaxies for the first time.

“The abundance of these low-mass galaxies during this period is so great that their collective impact could change the state of the universe,” Atik stressed. “Despite their small size, these galaxies produce extremely energetic radiation.”

The research involved taking ultra-deep images followed by spectroscopic analysis, confirming that these galaxies produced enough radiation to dispel the “tyranny of light” of the primordial gas in the early universe.

“This highlights the importance of understanding low-mass galaxies in shaping the history of the universe,” Chemerinska added.

This is just the beginning of what JWST could study in the future. Another program, GLIMPSE (Gravitational Lensing Imaging and NIRCam for Investigating Sources of Galaxy Formation and Early Reionization), in which Atek is the principal investigator, aims to explore an era known as the Cosmic Dawn, when the universe was only a few million years old.

These results open new doors to understanding the formative processes of the early universe and demonstrate the unparalleled power of JWST to probe these distant eras with unparalleled precision.