Monday , May 29 2023

The newly discovered giant satellite galaxy outside the galaxy, dark matter can fill it | TechNews


Astronomers have only discovered until now that a Nostra, Antlia 2 galaxy is hiding in the Milky Way. It is nearly as large as the Large Magellanic Cloud (LMC), but the overall brightness is 10,000 times as much as it has escaped astronomy many times. Home trial. In addition, the galaxy is large enough, but there are several stars in the galaxy, which can cause the formation of both galaxies and dark matter models, which is very exciting for astronomers.

Members of this international team include the Cambridge University Astronomy Institute, the Imperial College of Technology in London, Carnegie Mellon University and Dr. Gabriel Torrealba (the lead author of the study) working at Academia Sinica Institute of Astronomy and Astrophysics.

Initially, Gabriel Torrealba decided to project and analyze the "star of RR Lyrae" from Gaia data from the European Space Agency. These ancient metals poor stars are the main members of the dwarf galaxies in the Milky Way. The variable stars Lyra RR are widely distributed in the galactic plane, silver halo and spheroidal clusters. Since the brightness of the RR star type is relatively high, it is easy to trace the observations, it can be used to determine the distance between the spherical groups of the Milky Way and the adjacent galaxies and then to study the age of the spherical groups, stars, dynamics and evolution of the Milky Way.

However, because the Lyra RR variable star is quite rare, Vasily Belokurov, an astronomer and co-author of the University of Cambridge, UK, said: "If you see two at a time, you will doubt how it will be together" is at 420,000 years of bright years When I saw three Lyra RR, I felt surprised that this amount was "overwhelming" compared to the amount of the stars in the area.

The team began to observe the position of the RR-type variable stars in the sky and was surprised to find a large number of new objects that had no records in any database. After measuring the spectrum of more than 100 red giant stars, the researchers eventually confirmed the imaginary Antlia 2 galaxies that existed in the Milky Way region. Most of the stars were pulled by the gravitational attraction of the galaxy, and the entire galaxy blew 130,000 light-years from the Galaxy.

▲ Brightness comparison between the Antlia 2 Galaxy, the Galaxy and the Magellanic Cloud. (Source: China Academy of Sciences)

The researchers also calculated the quality of the galaxy, but in terms of magnitude comparable to the Large Magellanic Cloud (LMC), this quality is quite small (100 times lower than any similar galaxy size), at present, The Galaxy Theory does not explain why the Antlia 2 galaxies are so large, but the number of stars is so small.

Previous studies have shown that many new stars explode gasses and dust from the galaxy after a violent explosion of supernovae, which can cause the whole galaxy to swell, so it appears to be larger in size. However, the group believes it is difficult to explain the disproportionate size of the Antlia 2 galaxy.

With this in mind, the researchers say it may be necessary to re-examine the obscure dark matter that theoretically maintains a galaxy that is disproportionate in size and mass, says Dr. Alex Geringer-Sameth, Department of Physics, Imperial College London, UK, Antlia 2 Galaxies may have some new basic forces at work, and dark matter may not be as simple as the standard cosmological model.

Dr. Matthew Walker, co-author of Carnegie Mellon University, pointed out that we would like to know that the Antlia 2 dwarf galaxies are unique or just the tip of the iceberg. Is it possible for the Milky Way to be filled with a large number of almost invisible dwarf galaxies?

(Source of the first image: Academia Sinica)

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