Most of the stars of the universe today are found in elliptical ellipses, called ellipticals, named for their dispersion-cycle shape. Unlike our own galaxy, which is a spiral with arms extending from the center, the edges of elliptical galaxies are smooth.
At first glance, these galaxies may look like ordinary systems. However, they are one of the most mysterious objects in the universe. Hosts elliptical galaxies Very old stars And not making new stars.
How these dead galaxies actually form is a question that both observational and theoretical astronomers have tried to answer. For a long time. Our new study, Published in Nature Astronomy, can help solve this puzzle.
Make stars When huge clouds of gas within galaxies collapse under gravity. Eventually, enough mass gets together, and a star is formed. But for this to happen, galaxies need gas. Our team detected a galaxy, called ID2299, rejecting half of its star-forming gas. The galaxy is exhaling the equivalent of 10,000 suns per year in gas, destroying 46% of the galaxy’s total cold gas.
Because the galaxy is also forming stars very quickly, hundreds of times faster Compared to our Milky WayThe gas that is left will drink quickly. At current rates, ID2299 will be discontinued in only a few tens of years. This is much faster than the typical period of episodes of star formation in galaxies, which is a few billion years.
This exceptionally large-scale ejection is caused by a tidal tail, formed by the galaxy’s merger with another galaxy. Tidal tails extend into the interstellar space in the interstellar space of stars and gases, as a result of tidal forces caused by the interconnection – the Moon’s tidal-like stretch on Earth.
Tidal tails are commonly seen in nearby merged galaxies, but they are difficult to detect in distant universe due to their low brightness. Fortunately, even though ID2299 was seen at a time when the universe was only 4.5 billion years old (our universe is now about 14 billion years old), we were able to see this rejection when it first started, when these tails They usually have their luster.
We discovered this extraordinary galaxy with a survey of galaxies formed along it Atacama Large Millimeter / Submillimeter Array (ALMA), Designed to study the properties of cold gas in more than 100 galaxies in the distant universe.
The data from ALMA provided a spectrum of cold, star-forming gas. The ejection was seen as a broad emission line near the very prominent emission line associated with the galaxy. From this spectrum, we were able to measure the mass and velocity of the extracted gas.
This is the first time we have observed a typical massive star-forming galaxy in the distant universe that is about to die due to a large scale cold gas. Our study provides an important overview of the fact that galaxies can stop the formation of stars as a result of gas expulsion.
Simulations and previous observational results suggested that the gas ejectors were associated with the galactic winds produced by the accretion of gas Supermassive Black Hole Or intense star formation episodes. In our study, we showed that ejections detected in ID 2299 cannot be explained by a galactic wind. Therefore the results may prompt us to revise our understanding of how galaxies stop forming their stars.
Our study suggests that mergers have an important role in the evolution of galaxies because they are capable of ejecting large amounts of gas from galaxies, shutting down star formation and affecting galaxy evolution.
Future studies with deeper and higher resolution data will allow us to better understand the dynamics of the rejected gas in ID2299. Seeing more evictions in other distant galaxies will also be important to understand how common these events are.
By this article Annagrajia Puglisi, Post Doctor Research Associate Center for Extragalactic Astronomy, Durham UniversityRepublished from chit chat Under a Creative Commons license. read the Original article.
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