Scientists Are Perplexed to Find a Galaxy Without Dark Matter

Could this find contradict years of dark matter theories?
Loukia Papadopoulos

Dark energy and dark matter are believed to make up almost 95% of our universe. We are still unsure about what they are or where they come from but we believe they hold galaxies together with their gravity.

That's why we were shocked to find out astronomers spotted a perplexing galaxy without the ever-elusive matter, according to Gizmodo. It all began three years ago when Filippo Fraternali, an astronomer at Kapteyn Astronomical Institute of the University of Groningen in the Netherlands, and his colleagues first came across a few diffuse galaxies that looked as though they lacked dark matter.

The researchers decided to examine one of them in detail. They picked one about 250,000 light-years away, called it AGC 114905,  and used the 27 radio telescope antennas of the Very Large Array in New Mexico to study it.

After a detailed investigation, they came to the following conclusion. “The dark matter content that we infer in this galaxy is much, much smaller than what you would expect,” said Fraternali. The find is perplexing, to say the least. But it's not the first of its kind.

Not the first of its kind

Pieter van Dokkum, an astronomer at Yale, and his colleagues spotted similar galaxies in 2018 using the Hubble telescope. So why haven't they been more discussed?

Fraternali's galaxies and others like them have come to be called “ultra-diffuse galaxies.” They’re extremely spread out but have few stars and are almost so transparent that they’re difficult to investigate. “They’re slightly fainter in the center, so they’re difficult to detect. Now, with better telescopes and deeper observations, they have become more well known,” Mireia Montes, an astronomer at the Space Telescope Science Institute in Baltimore and an expert on such galaxies, told Gizmodo.

So does AGC 114905 and galaxies like it indicate a problem with conventional dark matter theories? It's too early to know yet. More research needs to be done including the use of the James Webb Space Telescope. One thing is for sure though: what we discover will be scintillating!

The study is published in the Monthly Notices of the Royal Astronomical Society.

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