This Webb Image Shows More Than 45,000 Galaxies, Reveals Secrets Of Early Universe And Stars

An investigation into galaxies that existed 500 to 850 million years after the Big Bang found that early galaxies were very good at creating bright, massive stars which pumped out ultraviolet light.

The world's most powerful space telescope, also called Webb, has captured an image which shows 45,000 galaxies at the same time, and has helped scientists decode interesting mysteries and secrets of the early universe and stars.

Source : NASA/ESA/CSA

James Webb Space Telescope has been surprising the world with its jaw-dropping images since July last year. Now, the world's most powerful space telescope, also called Webb, has captured an image which shows 45,000 galaxies at the same time, and has helped scientists decode interesting mysteries and secrets of the early universe and stars. The JWST Advanced Deep Extragalactic Survey (JADES), which is one of the largest programmes in Webb's first year of science, and will use at least 32 days of telescope time to discover and characterise faint, distant galaxies, has already discovered hundreds of galaxies that existed in the early universe, when it was 600 million years old. 

The JADES team has also found galaxies which were bubbling with young, hot stars. 

In a NASA statement, Marcia Rieke, co-lead of the JADES Program, said with this survey, astronomers want to answer questions such as how the earliest galaxies assembled themselves, how fast they formed stars, and why some galaxies stop forming stars. 

Early Galaxies Formed Massive Stars

An investigation into galaxies that existed 500 to 850 million years after the Big Bang, a time known as the Epoch of Reionization, found that early galaxies were very good at creating bright, massive stars which pumped out torrents of ultraviolet light. The Epoch of Reionization was an era which occurred more than 13 billion years ago, when the gas between galaxies was opaque to energetic light, making it difficult to observe young galaxies. Then, some unknown events caused the fog to clear and the universe to become completely ionised, or transparent, which is why astronomers mostly find "clear" conditions in much of the universe today. This phenomenon of disappearance of the universe's fog is called reionization. It is not yet clear whether galaxies full of hot, young stars, or active, supermassive black holes were the primary reasons behind reionization. 

The investigation was led by Ryan Endsley of the University of Texas at Austin. Endsley and his colleagues studied galaxies as part of the JADES program, using Webb's Near-Infrared Spectrograph (NIRSpec) instrument. 

They used the instrument to search for signatures of star formation, and found hot, young stars in abundance. 

In the NASA statement, Endsley said almost every single galaxy from the early universe they found using NIRSpec shows unusually strong emission line signatures which indicate intense recent star formation. 

According to NASA, the torrents of ultraviolet light pumped out by bright, massive stars transformed the gas from opaque to transparent by ionising the atoms, or removing electrons from their nuclei. The early galaxies had a large population of hot, massive stars, and these may have been the primary driver of the reionization process. Later on, the electrons and nuclei reunited, and this produced the strong emission lines observed by NIRSpec.

There were some periods when the young galaxies rapidly formed stars, and some quiet periods when fewer stars were formed, the investigation found. Since the galaxies had to capture huge clusters of gaseous raw materials to form stars, it is likely that the quieter periods occurred during the preparation phases. 

Another reason behind the quieter phases could have been the fact that massive stars quickly explode, because of which they are likely to have injected energy into the surrounding environment periodically, and the energy may have prevented gas from condensing to form new stars. 

Galaxies From The Early Universe

Not only is the JADES Program searching for early galaxies with young stars that existed 500 to 859 million years after the Big Bang, but also looking for galaxies that existed when the universe was less than 400 million years old. The aim is to explore how star formation in the early years after the Big Bang was different from the process seen in current times.

Due to the expansion of the universe, the light from faraway galaxies is stretched to longer wavelengths and redder colours in a phenomenon known as redshift. Astronomers can determine how far away a galaxy is by measuring its redshift.  

With the help of the JADES Program, astronomers have discovered about a thousand extremely distant galaxies. 

As part of a JADES investigation, Kevin Hainline of the University of Arizona in Tucson and his colleagues identified more than 700 candidate galaxies that existed when the universe was between 370 million and 650 million years old, using Webb's Near-Infrared Camera (NIRCam).