Based on the Big Bang cosmology and the LCDM model, the most widely accepted models for the beginning of the universe, scientists theorize that a huge cloud of neutral hydrogen permeated the universe. From this material, the first stars and galaxies rapidly formed over the next several hundred eons, an event that astronomers and cosmologists refer to as the “dawn of the universe.” For a while, it was further theorized that these early galaxies were surrounded by a giant halo of hydrogen gas called the Lyman-alpha nebula.<\/p>\n
In theory, these galaxies would have needed vast reservoirs of hydrogen gas to form rapidly. But until recently, astronomers had found evidence of only a few thousand of these clouds. Now, using data from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) at the University of Texas at Austin-McDonald Observatory, a team of astronomers has discovered tens of thousands of halos that existed 10 to 12 billion years ago, coinciding with the dawn of the universe.<\/p>\n
The research was led by Erin Mentach Cooper, HETDEX data manager, and Carl Gebhardt, HETDEX principal investigator and head of the astronomy department at the University of Texas at Austin. They included researchers from the Institute for Gravity and Space Studies (IGC), the Kavli Institute for the Physics and Mathematics of the Universe (IPMU), the National Astronomical Observatory of Japan (NAOJ), the Potsdam Leibniz Institute for Astrophysics (AIP), and several universities. A paper describing their findings recently astrophysical journal<\/em>.<\/p>\n *Hobby \u2013 Eberly Telescope Dark Energy Experiment (HETDEX) outside of Austin, Texas. Credit: HETDEX\/UT Austin*<\/p>\n HETDEX was designed to map the locations of more than 1 million galaxies during its three-year nominal mission to measure the effects of dark energy. By statistically combining the spectra of thousands of distant galaxies (a technique known as “stacking”), researchers can detect very faint spectral features that cannot be detected in individual galaxies. Hydrogen gas is very difficult to detect because it does not produce light on its own, but it glows in the presence of galaxies and stars that emit bright ultraviolet light.<\/p>\n Detecting this glow requires specialized observatories with precise instruments that can monitor the same part of the sky. “The Hobby-Eberly Telescope is one of the largest telescopes in the world,” said Postdoctoral Researcher Dustin Davis, HETDEX scientist and co-author of the study. “And the instruments used by HETDEX produce 100,000 spectra with each observation. So we have a huge amount of data and all sorts of nice, fun, weird things waiting for us to discover.”<\/p>\n Previous studies detected only a few thousand halos (about 3,000) because the instruments were too sensitive to detect all but the brightest examples. Additionally, observations of early galaxies have been greatly magnified to eliminate interference from large numbers of foreground objects, with only the smallest halos visible. For this reason, the range from small halos to the most extreme halos has remained elusive to astronomers.<\/p>\n “We’ve been analyzing the same small number of objects for the past 20 years or so,” Cooper said. “With HETDEX, we’re able to find many more halos and measure their shapes and sizes. This allows us to create a really impressive statistical catalog.” Of the 1.6 million early galaxies identified so far by HETDEX, the researchers selected the brightest 70,000 and analyzed them on a supercomputer at the Texas Advanced Computing Center (TACC) looking for signs of surrounding halos. <\/p>\n Although nearly half of the candidates did so, Cooper and her team suspect that the faintest systems may not be bright enough to reveal their true size. In addition to increasing the number of known hydrogen gas halos by a factor of 10 (approximately 3,000 to 33,000), this study also increases the range of known sizes. The newly revealed halos are tens to hundreds of thousands of light-years in diameter and envelop individual galaxies and galaxy clusters.<\/p>\n “We collected nearly half a petabyte of data not only on these galaxies, but also on the region in between,” Gebhardt said. “Our observations cover an area of \u200b\u200bthe sky where more than 2,000 full moons can be observed. The extent is vast and unprecedented.” Not only does this confirm that these halos are not a rare phenomenon, but it also provides a more representative sample for astronomers studying the early universe. The research team hopes their findings will help scientists study how the early universe evolved and conduct more detailed studies of the physics and mechanics governing hydrogen halos.<\/p>\n Details: HETDEX<\/em><\/p>\n<\/p><\/div>\n #Early #galaxies #surrounded #giant #clouds #hydrogen #astronomers #discovered #massive #clouds #hydrogen<\/p>\n","protected":false},"excerpt":{"rendered":" Based on the Big Bang cosmology and the LCDM model, the most widely accepted models for the beginning of the universe, scientists theorize that a huge cloud of neutral hydrogen permeated the universe. From this material, the first stars and galaxies rapidly formed over the next several hundred eons, an event that astronomers and cosmologists … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":495,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[689,687,690,684,685,557,688,691,686],"class_list":["post-494","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","tag-astronomers","tag-clouds","tag-discovered","tag-early","tag-galaxies","tag-giant","tag-hydrogen","tag-massive","tag-surrounded"],"_links":{"self":[{"href":"https:\/\/hyokal.com\/index.php?rest_route=\/wp\/v2\/posts\/494","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hyokal.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hyokal.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hyokal.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hyokal.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=494"}],"version-history":[{"count":0,"href":"https:\/\/hyokal.com\/index.php?rest_route=\/wp\/v2\/posts\/494\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hyokal.com\/index.php?rest_route=\/wp\/v2\/media\/495"}],"wp:attachment":[{"href":"https:\/\/hyokal.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=494"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hyokal.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=494"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hyokal.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=494"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"A](\"https:\/\/hyokal.com\/wp-content\/uploads\/2026\/04\/Early-galaxies-were-surrounded-by-giant-clouds-of-hydrogen-and.png\"\/)
A giant halo of hydrogen gas found in the HETDEX data is superimposed at that location, as seen in the JWST deep images. Credit: Erin Mentuch Cooper (HETDEX). NASA\/ESA\/CSA\/STScI (JWST).<\/em><\/p>\n