Astronomers using the James Webb Space Telescope (JWST) have observed powerful gas outflows from galaxies that are no longer forming new stars, often referred to as "dead" galaxies. These galaxies, which existed about 1.3 to 2.3 billion years after the Big Bang, are massive and have ceased star formation. A new study, published in the journal Astronomy & Astrophysics, examined 23 of these galaxies and found evidence of gas being expelled outward at high speeds. This gas outflow is likely driven by energy from supermassive black holes at the galaxies' centers, which can heat and push gas away, preventing it from cooling and forming new stars. The research, led by Pengpei Zhu from the Cosmic Dawn Center in Copenhagen, focused on galaxies observed as part of the JWST's DeepDive survey program. The team studied galaxies with a redshift range of 2.82 to 4.62, which corresponds to the early universe. To detect the gas outflows, the researchers used the "sodium doublet" — a specific absorption line in the light spectrum caused by sodium atoms. They carefully removed sodium absorption caused by stars themselves using detailed models of the galaxies’ stellar populations. They also confirmed the detected signals through extensive simulations to ensure the results were not due to random noise. In their study, the team found excess sodium absorption in 13 out of the 23 galaxies, indicating gas outflows. Seven of these galaxies showed clear signs of gas moving toward Earth — a phenomenon called blueshift — suggesting the gas is escaping from the galaxy. However, the speed of this outflow is not high enough for the gas to escape the galaxy permanently. Instead, it is likely to fall back into the galaxy within a few million to hundreds of millions of years. Once this gas returns, it may contribute to renewed star formation in the future. One of the galaxies, named DD-236, exhibited the most extreme gas outflow rate ever measured beyond the nearby universe. This outflow was associated with an actively feeding supermassive black hole at the galaxy’s center. While only two of the 13 galaxies with outflows showed signs of active black holes, the two most extreme outflows were linked to such black holes. The study suggests that these outflows are not solely caused by recent black hole activity or bursts of star formation but may be the result of a combination of past black hole activity and ongoing galaxy mergers. This finding provides new insights into how galaxies transition from active star-forming systems to quiescent, or "dead," states.