Astronomers have solved the mystery of a galaxy containing 99.99% dark matter

The mystery of a galaxy that shouldn’t exist can now be solved. Dragon Fly 44, an obscure galaxy found in 2016 containing 99.99 percent dark matter, has been closely re-examined, showing lower and more normal proportions of dark matter.

This means that we do not need to modify our models of galaxy construction, so they will try to find out how they can produce extreme outlets – everything behaves normally, the researchers said.

“Dragon Fly 44 (DF44) has been an anomaly for so many years that cannot be explained by the current model of the galaxy’s structure,” said Timur Saifollahi, an astronomer at the Captain Astronomical Institute in the Netherlands.

“Now we know that previous results were wrong and DF44 is not exceptional. It’s time to move on.”

Dark matter is the real heart of cosmic pickling. We don’t know what it is. We cannot detect it directly, as it does not absorb, reflect, or emit any electromagnetic radiation. But, based on the way some objects rotate due to gravity – the rotation of galaxies, the way light is curved – we can say how many masses there are in galaxies. And there is more mass in the calculation of the common, detectable matter.

We call that missing mass dark matter. According to multiple measurements, about 85% of matter in the universe is dark, although the proportions in the galaxies vary according to type.

And that’s a key component of our best Galaxy build models. It is believed that the dark matter network can channel matter into galaxies in the early universe, and it is the global glue that holds the galaxies together.

DF44, located in a coma cluster of galaxies about 330 million light-years away, is a type known as an ultra-diffuse galaxy. It is much less bright than a galaxy; Its luminosity indicates that DF44 has 1000 times fewer stars than our home galaxy.

This made the 2016 measurement of its mass surprising. Astronomers led by Yale University astronomer Peter van Dokkum calculated the number of globular clusters around DF44, the ganse-packed spherical clusters of stars orbiting the GeFactic Center.

Since the number of globular clusters is connected to the mass of the galaxy (although we are not sure why), astronomers were allowed to calculate the mass of DF44 – and they discovered that it was almost as large as a galaxy.

Given the low number of stars in DF44, this suggests that the galaxy contains almost entirely dark matter, making it an extreme outlet. Probably too extreme.

Thus, Saifolli and his team have conducted a global cluster recalculation, using the same Hubble Space Telescope observation data as in the previous study. They applied strict parameters to determine which globular cluster DF44 is bound to, and eventually came out with a much smaller number.

“The fact that in our work we found only 20 globular clusters compared to the previously claimed comparison0, which is believed to have a significant reduction in the amount of dark matter in the galaxy,” said astrophysicist Ignacio Trujillo. Canary Islands.

“Moreover, with the number of globular clusters we have found, the amount of dark matter in Dragonfly 44 is in agreement with what is expected for this type of galaxy. The visible ratio of dark matter is no longer 1 in 10,000, but one in 300.”

This is not Trujillo’s first run-in with ultra-diffuse galaxies with unusual dark matter content. Last year, he discovered that two such galaxies, DF2 and DF4, had been found earlier (also by Van Dokkum and colleagues) and were likely to be common in lesser black matter. The measurement of low dark matter was due to incorrect calculation of distance. Improve the distance, and the two galaxies are no longer global freaks.

That is, he told ScienceAlert at the time, “We’ve probably found more outsiders who ignore cosmological models than humans have.” And at the same time Saifol E and his team have found.

“Our work shows that this galaxy is not so isolated or unpredictable,” said Michael Bisley, an astrophysicist at the Instituto de Astrofísica de Caneria. “This way models of galaxy construction can explain it without the need for refinement.”

But this show is not necessary. Following the Trujillo distance calculation, Van Dokkam and colleagues also calculated the distance from DF2 and DF4. These new analyzes have yielded results consistent with the team’s initial search, so we expect the discussion around DF44 to continue.

Such discussions are good for science. Whatever the outcome, trying to figure it out will help us improve our techniques for studying the cosmos. We will call it a net victory.

Research has been published in Monthly instructions of the Royal Astronomical Society.