The mystery of a galaxy that shouldn't have existed could now have a solution. Dragonfly 44, a faint galaxy that was found in 2016 to consist of 99.99 percent dark matter, has been closely re-examined, revealing a lower and more normal proportion of dark matter.
This would mean that we don't have to revise our models of galaxy formation to try to figure out how they could have produced such an extreme outlier - everything is behaving completely normally, the researchers said.
"Dragonfly 44 (DF44) has been an anomaly all these years that could not be explained with the existing galaxy formation models," said astronomer Teymoor Saifollahi of the Kapteyn Astronomical Institute in the Netherlands.
"Now we know that the previous results were wrong and that DF44 is not extraordinary. It is time to move on."
Dark matter is a real dilly of a cosmic pickle. We don't know what it is. We can't detect it directly, since it does not absorb, reflect, or emit any electromagnetic radiation. But, based on the way some things move around due to gravity - the rotation of galaxies, the way the path of light bends - we can tell how much mass there is in galaxies. And there's way more mass than can be accounted for in a census of normal, detectable matter.
We call that missing mass dark matter. According to multiple measurements, roughly 85 percent of the matter in the Universe is dark, although proportions in galaxies vary according to the type.
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