Latest news with #RUBIES-UDS-QG-z7
Indian Express
26-04-2025
- Science
- Indian Express
What is a dead galaxy? Astronomers spot one that stopped forming stars 700M years after Big Bang
More than 13 billion years after the Big Bang, astronomers have found the most distant galaxy ever seen using the James Webb Space Telescope (JSWT), except that this one has already stopped forming stars. The JWST spotted light from this newly discovered 'dead galaxy' called RUBIES-UDS-QG-z7,(the Red Unknowns: Bright Infrared Extragalactic Survey). It is said to be the most distant and massive 'dead galaxy' to have been found till date. The discovery was made by an international team, led by astronomers from the University of Geneva (UNIGE) in Geneva, Switzerland. 'For a long time, scientists thought that only actively star-forming galaxies should be observed in the very early Universe. The James Webb space telescope now reveals that galaxies stopped forming stars earlier than expected,' according to a press release issued by the University on April 2, 2025. So, what is a dead galaxy? What leads to their formation? What is galaxy quenching? Why does the recent discovery matter? What is a dead galaxy? A galaxy that has stopped creating new stars is referred to as a 'dead galaxy'. This happens when a galaxy uses up its supply of gas, mainly hydrogen, which is essential for the birth of new stars. Without enough cold and dense gas, star formation becomes stagnant. Processes like stellar winds, supernovae, or black hole activity can also expel this gas. As a result, the galaxy slowly fades, filled with aging stars and no new ones to replace them. The oldest known 'dead' galaxy, JADES-GS-z7-01-QU, was spotted by the James Webb Space Telescope (JWST) in March last year. It stopped producing stars when the universe was just 700 million years old. How do galaxies grow and die? Galaxies grow by absorbing gas and converting it into new stars. A galaxy may be able to draw gas more effectively as its mass grows, which speeds up the formation of new stars as this growth is forever. Galaxies eventually go through a process known as 'quenching,' in which they stop forming stars and, in effect, stop growing. What is quenching? The biggest galaxies, which frequently have an elliptical shape, are particularly prone to quenching. Before star formation stops, these galaxies typically take a long period to form by building up large stellar populations. One of the most significant unsolved problems in astrophysics is what exactly causes galaxies to quench. 'Finding the first massive galaxies that stopped making stars in the early universe is important because it helps us learn how they were formed.' according to a research paper published by University of Geneva. 'Scientists found one such galaxy that made stars equal to 15 billion times the mass of the Sun, but stopped creating new stars,' it added. What next? At a distance of about 650 light-years, RUBIES-UDS-QG-z7's small physical size indicates a high stellar mass density that is equivalent to the maximum central densities found in quiescent galaxies at slightly lower redshifts (z ~2–5). It is possible that these galaxies will grow into the cores of the local universe's oldest and most massive elliptical galaxies. The Atacama Large Millimeter/submillimeter Array (ALMA), Earth's largest radio telescope project, which has 66 antennas situated in the Atacama Desert region of Northern Chile, may be able to assist the JWST in its research of RUBIES-UDS-QG-z7. 'The discovery of RUBIES-UDS-QG-z7 provides the first strong evidence that the centres of some nearby massive ellipticals may have already been in place since the first few hundred million years of the Universe,' the research paper read.
Yahoo
09-04-2025
- Science
- Yahoo
Record-breaking 'dead' galaxy discovered by JWST lived fast and died young in the early universe
When you buy through links on our articles, Future and its syndication partners may earn a commission. Using the James Webb Space Telescope (JWST), astronomers have found the most distant (and thus the earliest) massive "dead" galaxy to date. The discovery suggests that galaxies were "dying" much earlier in the universe than previously believed. "Death" for a galaxy refers to the slowing down, or even halting, of intense star formation, which stops a galaxy from growing. Such dead galaxies are more formally referred to as being "quiescent," or "quenched." Early dead galaxies seen by the JWST have been referred to as "red and dead" galaxies due to their lack of massive hot young blue stars and their abundance of old small red stars. They have also been dubbed "Little Red Dots" due to their appearance in JWST images. Light from this new record-breaking galaxy, designated RUBIES-UDS-QG-z7, has been traveling to us for 13 billion years, meaning the JWST saw it as it was just 700 million years after the Big Bang. That makes it the first so-called massive quiescent galaxy (MQG) seen in the infancy of the 13.8 billion-year-old universe. "We discovered a galaxy which formed 15 billion times the mass of the sun in stars and then stopped forming stars before the universe was only 700 million years old," team member Andrea Weibel of the University of Geneva (UNIGE) Department of Astronomy told "This makes RUBIES-UDS-QG-z7 the most distant massive quiescent galaxy known to date." The discovery may challenge our models of how galaxies evolve — and eventually stop growing — due to the cessation of star birth. "The observation implies that some galaxies have stopped forming stars when the universe was only 700 million years old," Weibel said. "So far, models and simulations contain very few such objects, more than 100 times fewer than the existence of RUBIES-UDS-QG-z7 suggests. This means that the physical processes and mechanisms that regulate star formation and its termination in galaxies in the early universe may have to be revisited." Quiescent galaxies are common immediately around the Milky Way. That's expected because the further away we look, the further back in time we are traveling. Thus, local massive galaxies have had a lot of time to start forming stars, grow to tremendous masses, and then exhaust the gas and dust needed for stellar construction, thus becoming quenched. We should expect more distant galaxies to still be enjoying their star-birthing youth. As the JWST has probed further and further back in time, however, it has discovered earlier and earlier MQGs. Several of these red and dead galaxies were found as early as 1.2 billion years after the Big Bang. Discovered as part of the "Red Unknowns: Bright Infrared Extragalactic Survey," or RUBIES, program, RUBIES-UDS-QG-z7 pushes the detection of MQGs back by another 500 million years. "Massive galaxies observed early in the universe only had a very limited amount of time to form their stars. This means they must have formed rapidly and efficiently, which helps us to constrain and, in some cases, even challenge theories and models of galaxy formation and growth," Weibel said. "RUBIES-UDS-QG-z7, however, is not only massive but has already stopped forming stars 50 to 100 million years before we observe it, while normal galaxies at these epochs are still building up their stellar mass through star formation." Weibel explained that the mass of RUBIES-UDS-QG-z7 and its reconstructed formation history suggest relatively efficient star formation for the galaxy. That does not directly challenge existing models of star formation. "The galaxy is very compact and may be an example of an object where a lot of gas and dust — the fuel of star formation — collapses and assembles into a small volume, where stars can form rapidly and efficiently for an extended period of time, or in multiple bursts," Weibel said. "What makes RUBIES-UDS-QG-z7 stand out is that it stopped forming stars so early on." This MQG may stand out from Little Red Dots seen by the JWST in ways other than its rapid death. "In the JWST images, RUBIES-UDS-QG-z7 resembled objects named Little Red Dots, which have been discovered with the JWST," Weibel said. "Many of these objects turned out to have strong emission lines and/or showed signs of active galactic nuclei (AGN). Thus, at least a good fraction of the light we observe from Little Red Dots may actually originate from accreting supermassive black holes, rather than stars."However, Weibel added that RUBIES-UDS-QG-z7 shows no signs of an AGN, meaning its light comes entirely from stars, not from the violent conditions around a feeding black hole. "This then implies its rather high mass and its quiescence, which both came as a big surprise," Weibel continued. "So far, we have only found one such object in all the JWST data that we investigated." From this, the team calculated that galaxies like RUBIES-UDS-QG-z7 should account for around one in 1 million galaxies. "This is, however, quite uncertain, because we don't know how lucky we got to find one in the small patch of the sky that we have scanned so far," Weibel said. "With hopefully many more years of JWST taking data, we will be able to search larger areas of the sky and get a better idea of how common galaxies like RUBIES-UGD-QG-z7 actually are." Related Stories: — Is our universe trapped inside a black hole? This James Webb Space Telescope discovery might blow your mind —James Webb Space Telescope finds our Milky Way galaxy's supermassive black hole blowing bubbles (image, video) — James Webb Space Telescope sees early galaxies defying 'cosmic rulebook' of star formation Performing higher resolution and deeper spectroscopy imaging of this galaxy could reveal the abundances of various elements, which would help better constrain the formation history of RUBIES-UDS-QG-z7. "We will get more data on this galaxy in the upcoming Cycle 4 of JWST observations. Specifically, higher resolution spectroscopy," Weibel JWST may need a helping hand to study RUBIES-UDS-QG-z7 from Earth's largest radio telescope project, the Atacama Large Millimeter/submillimeter Array (ALMA), which consists of 66 antennas located in the Atacama Desert region of Northern Chile."Data from the ALMA telescope at longer wavelengths of light can give us direct insight into the gas and dust content of the galaxy, which is closely related to its past and future star formation history," Weibel said. The team's research was published on April 1 in The Astrophysical Journal.
