Galaxies Without Dark Matter Are Real, Two New Studies Confirm

Last year, there were a lot of controversies around a claim that some galaxies don’t have dark matter. Now, this claim has been confirmed by two studies.

Both studies were conducted by teams led by Yale University’s Pieter van Dokkum, also who made the initial statement in March 2018.

Dokkum’s claim is based on the observation of NGC 1052-DF2 galaxy that he first spotted the year before. From the Hawaii-based Keck Observatory, Dokkum together with his colleagues noticed something strange in the way the globular clusters containing the galaxy were moving.

Their traveling speeds suggested that the galaxy’s total mass weighs the same as its visible matter components. Dark matter is invisible and accounts for a large proportion of the mass within the universe. If NGC 1052-DF2 had dark matter, the whole thing would move at a much higher speed.

Image from Keck Observatory

So it’s inevitable to conclude that the galaxy didn’t contain any dark matter, which is impossible.

When the study results came out in the journal Nature, there was skepticism, astonishment, and even anger.

Dokkum shared that sometimes it was stressful. He continued by stressing that the scientific process should work this way. When noticing something interesting that people disagree, a scientist will collect new data and end up learning even more about the universe. However, while most critics are polite and constructive, some are not. Dokkum added that with each new critique coming out, the team had to work and find what they might have missed.

However, the two latest papers have proved that they hadn’t missed anything.

NGC 1052-DF2 galaxy

One of them illustrating updated and further details observations of NGC 1052-DF2 using Keck, which was published in The Astrophysical Journal Letters. The study results confirm that the globular clusters of the galaxy moved at the same speed with what expected from just stellar mass.

With this result, one question left to answer is if this lack of dark matter happens to only this galaxy or more than that.

The second paper gave the answer, also published in The Astrophysical Journal Letters. Accordingly, NGC1052-DF2 is not the only galaxy to lack dark matter. This paper indicates the researchers’ discovery of a similar galaxy, dubbed NGC 1052-DF4.