When astronomers discovered that the galaxy contained 99.99% dark matter, many experts thought its existence was absurd. Then we have also solved the mystery of the galaxy Dragonfly 44: After carefully observing and analyzing its properties, scientists believe that the amount of dark matter here is not as much as initially stated.
That means researchers do not need to re-model the galaxy to fit the oddities of Dragonfly 44 (DF44). All concepts are on the correct orbit, researchers say.
“For many years, DF44 has remained an anomalous galaxy that our model cannot explain. Now we know that the previous measurements are wrong, and that the DF44 is nothing special. Now is the time to forget it“, Astronomer Teymoor Saifollahi working at the Institute of Astronomy Kapteyn of the Netherlands said.
Dark matter is another anomalous concept that we have not explained yet. We do not know what it is, nor can we detect it directly, because it does not absorb, reflect or emit electromagnetic radiation. However, based on the knowledge we know about objects moving through space under the influence of gravity as well as how light is bent in space, we can calculate the mass of matter in a celestial body. Ha. Obviously, the total mass present in a galaxy is greater than the total visible / measured mass.
We call the missing part dark matter. Based on numerous estimates and measurements, about 85% of the matter in the Universe is dark matter; However, this number will differ depending on the type of galaxy.
They are crucial for the scientific deduction of the model of galaxies. Scientists believe that lattice of dark matter can flow into galaxies from the very beginning of the Universe, and that they are the “colloids” that hold celestial bodies and systems in a galaxy together.
DF44 is located about 330 million light-years from the Coma Cluster, and is classified as an “ultra-diffuse galaxy”. It is less bright than the Milky Way, and its estimated number of stars is 1,000 times less than the number of stars in the Milky Way.
The galaxy DF44 and the Coma cluster.
Based on these estimates, the DF44 mass measurement released in 2016 gave scientists a headache. The team of astronomers led by Pieter van Dokkum counted clusters of spherical galaxies around DF44. Since the number of clusters is directly related to the mass of a galaxy (although it is not known exactly why), the team calculated DF44’s mass and found that the measurement was close to Galaxy.
Because the number of DF44 stars is so small, the team of scientists identified that DF44 is made up of a large amount of dark matter, up to 99.99%.
The absurdly large number led Saifollahi and his team to count the spherical cluster once again, using data observed by the Hubble Space Telescope. The team applied more rigorous calculations to quantify the DF44-related clusters, and came up with a different result than what the astronomer van Dokkum’s team had calculated.
“In fact, we have only found 20 spherical clusters, which are different from 80 before, reducing the amount of dark matter that is thought to be in DF44.“, Astrophysicist Ignacio Trujillo said.
“Furthermore, given the number of spherical clusters we counted, the amount of dark matter in Dragonfly 44 is consistent with the galaxy model we still have. The ratio of visible and dark matter was no longer 1 / 10,000, but became 1/300“.
Dark matter concept illustration.
This is not the first time that Trujillo has “encountered” a super-diffuse galaxy with an unusually high amount of dark matter. Last year, he discovered an error in the statement that “two galaxies DF2 and DF4 (also discovered by van Dokkum et al.) Have abnormally low amounts of dark matter”. It turned out that calculating the wrong distance made a mistake, and everything went back to normal with the correct indicator applied.
Everything is not over yet. After reading Trujillo’s results, van Dokkum et al also recalculated the distances associated with DF2 and DF4, and then came up with the same results as they had previously made, that these two galaxies contain very much less dark matter. Most likely, van Dokkum’s team is also re-measuring DF4 to continue to prove that they are still correct.
Controversy between groups of researchers will accelerate the rate of development of science. What is the result, the truth will still be honored, the way of understanding the Universe will be more complete after each word.
So you guys just keep on debating, humanity wholeheartedly supports.