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A group of astrophysicists have discovered the largest and most scattered galaxy ever recorded.
Nube is an almost invisible dwarf galaxy discovered by an international team of scientists led by the Instituto de Astrofísica de Canarias (IAC) in collaboration with the University of La Laguna (ULL) and other institutions.
The object’s name was suggested by the 5-year-old daughter of one of the group’s researchers and comes from the object’s scattered appearance. Its surface brightness is so faint that it has gone unnoticed in various previous surveys of this part of the sky, as if it were some kind of ghost. This is because the stars in this region are spread over such a large volume that the “Nube” (which means “cloud” in Spanish) was almost undetectable.
This newly discovered galaxy has unique properties that set it apart from previously known objects. The research team believes that Nube is a dwarf galaxy that is ten times dimmer than other objects of its kind with a comparable number of stars. For those interested in astronomy, it is worth noting that this galaxy is ⅓ smaller than the Milky Way, but has a similar mass to the Small Magellanic Cloud.
“With our current level of knowledge, we do not understand how a galaxy with such extreme features could exist,” explained Mireia Montes, lead author of the paper and a researcher at IAC and ULL.
Ignacio Trujillo, the second author of the article, has been analyzing a specific area of the sky for several years as part of the Legado del IAC Stripe 82 project, using images from the Sloan Digital Sky Survey (SDSS) program. While reviewing the data, they noticed a weak spot that seemed interesting enough to start a new research project.
The next step was to use ultra-deep multicolor images from the Gran Telescopio Canarias (GTC) to confirm that the faint spot in the study was not the result of a mistake, but an extremely diffuse object. Due to its weakness, it is difficult to determine Nube’s exact distance. The authors estimated Nube’s distance to be 300 million light-years, based on observations with the Green Bank Telescope (GBT) in the United States, but also future observations with the Very Large Array (VLA) radio telescope and the William Herschel Telescope ( WHT) in Roque The Observatory de los Muchachos on La Palma is intended to help determine whether this distance is correct. Ignacio Trujillo explained: If the galaxy turns out to be closer, it will still be a very strange object that poses a serious challenge to astrophysics.
The next challenge for the current dark matter model?
Typically, galaxies have a much higher density of stars in their inner regions, and this density decreases rapidly with distance from the center. However, Montes says so in the case of Nube The density of the stars varies very little throughout the object, which is why it is so faint and we couldn’t observe it well until we got ultra-deep images from GTC.
Nube surprised astronomers. The research team explains that at first glance there are no visible interactions or other signs of its strange properties. Cosmological simulations are unable to reproduce their “extreme” features, even when based on different scenarios. We are left with no real explanation within the currently accepted cosmological model, i.e. cold dark matter Montes explained.
The cold dark matter model can reproduce large-scale structures in the universe, but there are small-scale scenarios like the Nube case for which it cannot provide good answers. We have shown that various theoretical models fail to make this happen, making it one of the most extreme cases known to date. It is possible that with this and other galaxies we will find additional clues that open a new window into understanding the universe. Montes said.
One attractive possibility is that Nube’s unusual properties show us that the particles that make up dark matter have extremely low mass – said Ignatius Trujillo. If this were the case, the galaxy’s unusual properties would be a demonstration of the properties of quantum physics, but on a galactic scale. If this hypothesis is confirmed, it would be one of the most beautiful phenomena in nature, uniting the world of the smallest with the world of the largest. – he concluded.
Development:
Agnieszka Nowak
More information:
Source: IAC
Shown: An image of the Nube Galaxy from three different telescopes. Source: SDSS/GTC/IAC
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