In 2018, Yale University researchers published a groundbreaking study about galaxy NGC 1052-DF2 -- the first known galaxy with little or no dark matter. As NASA pointed out, the galaxy is as large as our Milky Way. The agency's Hubble Space Telescope was subsequently used to learn more about this mysterious and unique corner of the universe.
Nevertheless, Yale University researchers were still somewhat skeptical, which is why they decided to conduct two new studies. The first study ("Still Missing Dark Matter: KCWI High-resolution Stellar Kinematics of NGC1052-DF2"), published in The Astrophysical Journal Letters, confirmed the findings of the 2018 study, establishing that the NGC 1052-DF2 indeed has little or no dark matter.
The new study confirmed the findings of the 2018 study by establishing that the stars in the DF2 galaxy are moving much slower than they would move in a galaxy with dark matter.
"The fact that we're seeing something that's just completely new is what's so fascinating. No one knew that such galaxies existed," said study author Shany Danieli.
The second new study ("A Second Galaxy Missing Dark Matter in the NGC 1052 Group"), also published in The Astrophysical Journal Letters, lead to the discovery of another galaxy with no dark matter. The scientists named it DF4. Lead author of this study, Yale Professor Pieter van Dokkum, explained in a press release that a discovery of another galaxy devoid of dark matter means that there are likely other similar galaxies in space, which means that it is only a matter of time before they're discovered by other scientists.
"This means the chances of finding more of these galaxies are now higher than we previously thought," he said, adding that he hopes Yale's findings will encourage other scientists around the world to keep working on solving this space puzzle.
Furthermore, the significance of these new findings has prompted Yale University researchers to look for galaxies devoid of dark matter in a more systematic way.
Yale University researchers are now using the Dragonfly Telephoto Array -- a telescope they designed -- to look for similar galaxies. Their goal is to establish whether such galaxies exist in other areas of universe, they said, and gain a better understanding of what is one of the biggest mysterious of our universe.
"We want to find more evidence that will help us understand how the properties of these galaxies work with our current theories. Our hope is that this will take us one step further in understanding one of the biggest mysteries in our universe -- the nature of dark matter."