Yale-led team of researchers A doubling its earlier finding galaxies almost without dark matter.
In 2018, researchers published their initial study of galaxy NGC thousand fifty and two-DF2 – DF2 abbreviated – the first known galaxy contains little or no dark matter. The conclusion was significant because it showed that dark matter is not always associated with the traditional question of the galactic scale. He also ruled out several theories that consider the substance of dark matter entirely, but a manifestation of the laws of gravity on cosmic scale.
Invisible dark matter, as a rule, dominant in the galaxy. Stay on & # 39 object without dark matter was unprecedented and led to a fair amount of debate within the scientific community.
"If there is one on the & # 39; an object, there is always a little voice in the back of your mind says," But what if you're wrong? "Said team leader Pieter van Dokkum is, Sol Goldman something & # 39; I am a professor of astronomy at Yale University . "Even if we did all the tests, we could think of, we were concerned that the nature left us in the loop and conspiracy to make something look really special while it was actually something more mundane. "
Now it's time to new studies that a & # 39; appear in the Astrophysical Journal Letters journal supports the initial output of the command.
"The fact that we can see that it's just a completely new & # 39 is that it's fun," said Yale graduate student Shani Danieli, who first saw the galaxy about two years ago. "No one knew that there are galaxies, and the best in the world for astronomy students to discover on the & # 39; an object, whether it is a planet, star or galaxy that nobody knew about or even thought of."
Danieli with & # 39 is the lead author of one of the new studies. This confirms the initial observations of DF2 team, using more accurate measurements of W.M. Keck Observatory Keck Cosmic Web Imager. The researchers found that stars within the galaxy are moving at a speed corresponding to the mass of ordinary matter of the galaxy. If the dark matter in the DF2, stars will move much faster.
Van Dokkum with & # 39 is the lead author of another new study, detailing the opening of the second galaxy devoid of dark matter. This galaxy is called DF4.
"Open the second galaxy with very little to no dark matter just as exciting as the initial opening of DF2,» said van Dokkum. "This means that the chances of finding more of these galaxies is now higher than previously thought. Since we do not have good ideas about how galaxies are formed, these, I hope these findings will encourage more scientists to work on this puzzle. "
Both DF2 and DF4 with & # 39 are part of a relatively new class of galaxies called Ultra-diffuse galaxy (UDGs). They are as large as the Milky Way, but have 100 to 1000 times fewer stars. This makes them fluffy and translucent – and difficult to observe.
Oddly enough, the lack of dark matter in these UDGs strengthens the case for dark matter, researchers say. This proves that dark matter is a material, which is not combined with a conventional material, since they can be found separately.
In addition to van Dokkum and Danieli, members of the team include Roberto Abraham of the University of Toronto, Aaron Romanovsky from San Jose State University, and Charlie Conroy of the Harvard.
Danieli is a broad overview of the field with Dragonfly telephoto Array – telescope designed van Dokkum – look for more examples on a systematic basis, and then observe the candidate again using the Keck telescopes.
"We hope that the next to find out how often these galaxies are and whether they exist in other regions of the universe," said Danieli. "We want to find more evidence that helps us understand how the properties of these galaxies to work with our current theories. Our hope is that this will bring us one step forward in the understanding of one of the biggest mysteries in our universe – the nature of dark matter. "
- Shani Danieli et al «Still Missing Dark Matter: KCWI high resolution Stellar Kinematics NGC1052-DF2». ApJL, 2019; DOI: 10,3847 / 2041-8213 / ab0e8c
- Pieter van Dokkum. etc. «A Second Galaxy Missing Dark Matter in NGC thousand fifty and two Group» ApJL, 2019. DOI: 10,3847 / 2041-8213 / ab0d92