Observation with The James Webb Space Telescope provided the first spectroscopic observations of the faintest galaxies during the first billion years of the universe.
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These findings help astronomers answer an age-old question: what sources caused the reionization of the universe?
These new results effectively demonstrated that small dwarf galaxies They are likely producers of enormous amounts of energetic radiation, according to NASA’s website dedicated to the telescope.
Research into the early evolution of the universe is an important aspect of modern astronomy. In any case, much remains to be understood about a moment in the early history of the universe known as the era of reionization.
It was a period of darkness without stars or galaxies, filled with a thick fog of hydrogen gas, until the first stars ionized the gas around them and light began to travel through them.
Astronomers have spent decades trying to identify the sources that emitted radiation strong enough to gradually clear away this hydrogen fog that blanketed the early universe.
The Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization (UNCOVER) program (#2561) consists of images and spectroscopic observations of the lens cluster Abell 2744.
An international team of astronomers used gravitational lensing, also known as Pandora’s Summit, explore the sources of the reionization period of the universe.
Gravitational lensing magnifies and distorts the appearance of distant galaxies, making them look very different from those in the foreground.
The “lens” of the galaxy cluster is so massive that it distorts the structure of the universe itself to such an extent that light from distant galaxies passing through the warped space also takes on a warped appearance.
The magnification effect allowed the team to study very distant light sources beyond Abell 2744, revealing eight extremely faint galaxies that would otherwise have been undetectable even to Webb.
The team found out These faint galaxies are huge producers of ionizing radiation, at a level four times higher than previously thought. This means that most of the photons that reionized the universe probably came from these dwarf galaxies.
“This discovery reveals the crucial role played by ultra-faint galaxies in the early evolution of the universe,” said Iryna Chemerynska, a team member from the Paris Institute of Astrophysics in France.
“They produce ionizing photons that transform neutral hydrogen into ionized plasma during cosmic reionization. “It highlights the importance of understanding low-mass galaxies in shaping the history of the universe.”
“Together, these cosmic powers put out more than enough energy to get their work done,” added team leader Hakim Atek of the Paris Institute of Astrophysics, CNRS, Sorbonne University, France and lead author of the paper describing the result.
“Despite their small size, these low-mass galaxies are fertile.” energy radiation producers, and their abundance during this period is so considerable that their collective influence may change the whole state of the Universe.’
To reach this conclusion, the team first combined data from the Ultra-Deep Webb images with the companion images of Abell 2744 from the NASA/ESA Hubble Space Telescope to select extremely faint candidate galaxies in the epoch of reionization.
This was followed by spectroscopy with the Webb Near Infrared Spectrograph (NIRSpec). The instrument’s multi-trigger array is used to obtain multi-object spectroscopy of these faint galaxies.
This is the first time scientists have thoroughly measured the number density of these faint galaxies. and successfully confirmed that they are the most abundant population at the time of reionization. This is also the first time that the ionizing power of these galaxies has been measured, allowing astronomers to determine that they produced enough energetic radiation to ionize the early universe.
“The incredible sensitivity of NIRSpec, combined with the gravitational amplification provided by Abell 2744, allowed us to identify and study in detail these galaxies from the first billion years of the universe, even though they are more than 100 times fainter than our own Milky Way,” continued Atek.
