There are hundreds of billions of galaxies in the universe, each containing billions of stars and located in every part of the sky. But in some directions, nearby galaxies block the view of the more distant universe. Now a team from the University of Keele has created the largest map of previously hidden galaxies to date. Jessica Craig will present her work at the National Astronomy Meeting at the University of Warwick this week. Astronomers looked at the Magellanic Clouds, a pair of galaxies visible from the Southern Hemisphere that are so close to us that they can be seen with the naked eye. These two galaxies occupy a large area of ​​the sky and block the view of galaxies further away. For this reason, astronomers searching for distant galaxies usually avoid this part of the sky.
Using the VISTA Survey Telescope in Chile, the team photographed two nearby galaxies at high enough resolution to view the gaps between the stars in each. This way, they could see more distant galaxies that appear fainter and redder than they actually are because of the dust still in front of them.The solution is to use a radio telescope, and in this case, the Galactic Australian Square Kilometer Array Pathfinder Survey (GASKAP) provides a detailed map of the gas in the Magellanic Clouds, allowing us to measure the dust content and thus how reddened the stars are.
Another problem is distinguishing stars from galaxies, and there are so many of them that it would be impossible to do manually. So Keele’s team used data from the Gaia observatory to measure tiny shifts in the positions of stars over time, while much more distant galaxies remained in the same place. Galaxies are also redder than brighter stars, so the color helped remove more stars from the dataset. The color also shows how far away the galaxies are (via their redshift resulting from the expansion of the universe).Machine learning, where software uses artificial intelligence tools, does the final kind of rest of the data. All this work leads to the largest 3D map to date of galaxies previously hidden behind the Magellanic Clouds, covering an estimated 1 million galaxies.
Jessica Craig comments: “The Magellanic Clouds are wonderful galactic companions, but unfortunately they block some of our view of objects further out. Our work helps overcome this and in the process helps fill in the gaps in our map of the universe.”
For more Read: https://ras.ac.uk/news-and-press/news/beyond-clouds-finding-galaxies-behind-galaxies
