The hidden source of the mysterious glow in the early universe has finally been revealed: ScienceAlert

The hidden source of the mysterious glow in the early universe has finally been revealed: ScienceAlert

The early universe was a dark place. It was filled with hydrogen, which blocked out the light and nothing else.

Only when the first stars lit up and began illuminating their surroundings with ultraviolet light did light begin its reign. This happened during the era of reionization.

But before the universe became well-lit, a specific, mysterious type of light broke through the darkness: Lyman alpha emissions.

Although the early universe was too dark for light to travel through the opaque gas that dominated it, astronomers still detected some Lyman alpha lines before the lights appeared in the era of reionization.

From where he came? This has been an important unanswered question that many have thought about.

Galaxy EGSY8p7, a bright galaxy in the early Universe where light emission is seen from, among other things, excited hydrogen atoms – Lyman alpha emission. In the lower two panels, Webb’s high sensitivity captures this distant galaxy along with its two companion galaxies, where previous observations had only seen one larger galaxy in its place. (ESA/Web, NASA and CSA, S. Finkelstein, M. Bagley, R. Larson/UT Austin/A. Pagan/STScI/C. Witten, M. Zamani)

Lyman alpha emissions occur in the ultraviolet range and come from hydrogen atoms when their electrons transition to a certain energy state. The Lyman-alpha spectral lines are part of what astronomers call the Lyman-alpha forest.

A forest is a series of absorption lines originating from hydrogen found in distant astronomical objects. When its light passes through gas clouds of different redshifts, it creates a forest of Lyman-alpha lines.

“Providing an explanation for the surprising discovery of Lyman-alpha in these early galaxies represents a major challenge for extragalactic studies,” write the authors of some of the new research.

The research is published in Nature astronomy Maybe you found the answer. Its title is “Deciphering Lyman alpha emission in the deep epoch of reionization.” Lead author is Callum Witten, a researcher at the Kavli Institute of Cosmology at the University of Cambridge in the United Kingdom.

“One of the most puzzling issues presented by previous observations is the detection of light from hydrogen atoms in the very early universe, which should have been completely obscured by the original neutral gas that formed after the Big Bang,” Witten said at a press conference. launch.

“Several hypotheses have been previously proposed to explain the Great Escape of this ‘inexplicable’ emission.”

But now there’s a new cosmic mayor in town: the James Webb Space Telescope.

The James Webb Space Telescope: humanity's new favorite scientific instrument.  Image credit: NASA
The James Webb Space Telescope: humanity’s new favorite scientific instrument. (NASA)

The James Webb Space Telescope (JWST) was built with the ability to travel back to the early days of the universe. That was one of the primary motivations for the whole endeavor.

The ability of the James Webb Space Telescope to sense photons from stars in the first galaxies early in the life of the universe has opened a new window on the early universe and leads us toward answers to many long-standing questions. The James Webb Space Telescope has the sensitivity and angular resolution to track ancient light back to its source.

“Here, we uniquely take advantage of both high-resolution and high-sensitivity images from the James Webb Space Telescope near infrared camera to show that all galaxies in a sample of Lyman alpha emitters with redshift > 7 have close companions.” Writing in their paper. This is an important point and has major implications.

JWST images of the Lyman-Alpha LAE emitter EGSY8p68 reveal more detail than previous observations by the Hubble Space Telescope. The resolving power of the James Webb Space Telescope reveals a cluster of smaller, fainter galaxies around bright galaxies in LAE EGSY8p68 that the Space Telescope’s telescope could not see. The region is a busier and more crowded region with a lot of active star formation.

“While Hubble saw only a large galaxy, Webb saw a group of smaller interacting galaxies, and this discovery had a major impact on our understanding of the unexpected hydrogen emission from some of the first galaxies,” said study co-author Sergio Martin. -Alvarez from Stanford University.

Early galaxies were prodigious star producers and were a rich source of Lyman alpha emissions. Most of the emissions were masked by the primordial neutral hydrogen that filled intergalactic space in the early universe. What does it tell us that most Lyman-alpha emitters (LAEs) are galaxies with close neighbors?

According to the authors, it tells us that galaxy mergers and abundant star formation are the reason behind Lyman-alpha emissions. The galaxy merger simulation produced a mock JWST image that looks remarkably like an actual JWST image of interacting galaxies.

This figure from the study helps explain some of the findings.  The upper left panel and lower left panel are two images of LAE EGSY8p68.  The upper part is from the James Webb Space Telescope (JWST), and the lower part is from the Hubble Space Telescope.  The more powerful James Webb Telescope has revealed some nearby galactic companions of LAE EGSY8p68.  b to e are images from a galaxy merger simulation called Azahar.  Two of those simulated images are mock images of what the James Webb Space Telescope would see if it were observing a merger.  These two images are very similar to the real JWST image in the file.  Image credit: Witten et al.  2023.
This figure from the study helps explain some of the results. The upper left panel and lower left panel are two images of LAE EGSY8p68. The upper part is from the James Webb Space Telescope (JWST), and the lower part is from the Hubble Space Telescope. The more powerful James Webb Telescope has revealed some nearby galactic companions of LAE EGSY8p68. b to e are images from a galaxy merger simulation called Azahar. Two of those simulated images are mock images of what the James Webb Space Telescope would see if it were observing a merger. These two images are very similar to the real JWST image in the file. The magenta in e shows the Lyman alpha emission intensity. (Whitten et al. 2023)

The researchers used simulations of galactic mergers and interactions called “blossoms” to test their idea. Al-Azhar showed that as stellar mass accumulated and stars formed in these early galaxies, two things happened.

The stars released Lyman alpha emissions, creating bubbles and channels of ionized hydrogen in the neutral hydrogen that blocked out the light. Bubbles and channels allowed Lyman alpha emissions to pass through.

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This research shows that there were many more galaxy mergers in the early universe than we could see before the James Webb Space Telescope was launched.

These mergers and interactions and the abundant star formation they induced are responsible for creating Lyman alpha emissions and creating a path for them to emerge from the dense, opaque neutral hydrogen that dominated the young universe.

In short, the high rate of galactic merger in the young universe is responsible for the mysterious Lyman alpha emissions.

The researchers aren’t finished yet. They are planning more detailed observations of galaxies in different stages of merger to develop their idea further.

This article was originally published by Universe Today. Read the original article.

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