Dark matter is a powerful cosmological model, but it is not without problems. In addition to our inability to detect dark matter particles, one problem concerns the number of dwarf galaxies surrounding the Milky Way. According to the most popular dark matter models, galaxies should be surrounded by clumps of dark matter within dark matter halos. Since ordinary matter tends to cluster around dark matter, this means that the Milky Way must be surrounded by dwarf galaxies.

Although there are a few known dwarf galaxies near the Milky Way, they are fewer in number than dark matter simulations predict. But there may be many more dwarf galaxies that we don’t notice because they consist mostly of dark matter.

We discovered a few of these. These are known as near-dark galaxies (ADGs) and are particularly faint. We haven’t found enough of them to fit the cold dark matter model, but we keep finding them, as a recent study shows.

It describes a recently discovered dwarf galaxy known as Nube. IAC Stripe82 was found by chance in images collected by the Legacy Project. It is so faint that it is not visible in the Sloan Deep Sky Survey (SDSS), which is somewhat surprising. However, the team noticed what appeared to be a dark galaxy in the image and decided to use the Green Bank telescope to investigate further.

The galaxy is about 350 million light-years away and has a surface magnitude of about 28 magnitudes per arcsecond, according to Greenbank. This galaxy is extremely dispersed, with half its mass being over 22,000 light-years away, nearly a quarter the diameter of the Milky Way.

It has a mass of about 26 billion solar masses, but the stars in the galaxy have a mass of only 390 million solar masses. The galaxy consists mainly of dark matter and is the largest known ultra-diffuse galaxy.

It was just by chance that we found this dark matter galaxy. Given its size, it’s likely that other dwarf galaxies lurk in our celestial neighbors if we could find them.

But surprisingly, while such galaxies support the dark matter cosmological model, this particular galaxy does not fit the profile of the most popular variable known as cold dark matter.

Instead, it best fits the version known as fuzzy dark matter. As we get closer to the predictions of dark matter simulations, it’s clear that there are a few surprises waiting to be discovered. That’s why we must continue to search for such galaxies. The answers to our questions about dark matter are certainly out there, huddled in the dark.