Researchers detect many supermassive black holes inside dying galaxies in our local universe – ABC17NEWS

By Alexandra Mae Jones

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Toronto (TVC network) — Supermassive black holes may have the power to “quench” star formation in their galaxies, according to a new study that has detected many supermassive black holes early in the life of our local universe. An international team of astronomers has combined data from some of Earth’s most powerful telescopes to piece together an idea of ​​how galaxies with little or no star formation might be related to black holes, by examining emissions radio galaxies more than 10 billion light years away from us for the very first time. The study, published in the Astrophysical Journal in April, compared data from stagnant galaxies to those from star-forming galaxies, and found that among older galaxies, those producing no stars were much more likely to die. have a supermassive black hole hidden in their center. In the known universe, there are countless galaxies in different stages of growth. Many massive elliptical galaxies in our local universe — which refers to a region around our solar system about 1 billion light-years in radius — are relatively stagnant, seeing little star formation. Modeling in previous research has suggested that these galaxies had an intense period of star formation early in their lives, followed by an abrupt downturn. But why are some galaxies still producing stars while others are stagnating? “It is not well understood which physical processes are responsible for the rapid quenching and suppression of subsequent star-forming activities,” the study says. One theory for the suppression of star formation is that radiation from an active galactic nucleus could interfere with the formation of new stars in that particular galaxy. An active galactic nucleus (AGN) is a small central point in a galaxy that has significantly higher luminosity and radiance than any other element in the galaxy, sometimes so bright that it completely eclipses the entire galaxy. AGNs are thought to surround a supermassive black hole, with radiation being the byproduct of this material devouring the black hole that gets too close. However, although it has been previously theorized that black holes may be linked to the slowing of star formation in galaxies, many questions remain. In this study, the researchers wanted to dive into this theory by looking at a broader spectrum of galaxies at once, including fainter and more distant ones that may not have been included in the research before. Because it takes a long time for light from distant galaxies to reach us, what we see when we look up into the sky is a snapshot of what those galaxies looked like millions, if not billions of years ago. The older and more distant a galaxy is, the more difficult it is to study. Because the signals from individual galaxies were too weak to identify, in this new study, the researchers stacked X-ray and X-ray images of the galaxies on top of each other to help filter out noise and get a better idea of ​​the average signal from these galaxies. Researchers selected the galaxies to examine using the latest data from the Cosmic Evolution Survey (COSMOS), an astronomical survey that focuses on a specific area of ​​the visible universe, covering more than two million galaxies, to study the formation and evolution of galaxies. The team, led by researchers in Japan, looked specifically at galaxies 9.5 to 12.5 billion light-years away. What the researchers found was that the X-ray luminosity of stagnant galaxies at least 12 billion light-years away from us was greater than that of star-forming galaxies at the same mass and at the same distance. But the X-ray signals and radio emissions from these stagnant galaxies could not be explained by their number of stars, indicating that this high luminosity came from an AGN, and therefore from a supermassive black hole. Stagnant galaxies were also more common in galaxy clusters or other denser parts of the universe than in the general field of space. The study also found that the tendency for stagnant galaxies to have brighter luminosity than star-forming galaxies was weaker among younger, closer-to-Earth galaxies, compared to those much farther away. The researchers speculated that this could be because other factors are impacting star formation in these closer galaxies instead of it being driven largely by the presence of a supermassive black hole. . “Our work hints at the evolutionary role of AGN feedback for galaxy extinction toward a higher redshift, and future observations of [stagnant galaxies] may shed more light on detailed physics,” the study said in its conclusions. Redshift is a term in astronomy referring to how far away an object is in space, with a higher redshift meaning it is farther from us. The researchers noted that there were still aspects of the data that could not be explained by AGNs alone, and that further research is needed to find out how and why black holes may be linked to the suppression of the formation of black holes. ‘stars.

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Tom Yun

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