Here’s the paper on it … out of Communist China …newly discovered dwarf galaxy located a mere 94 million light-years away is defying expectations. It's named FAST J0139+4328, and it's not emitting any optical light. In fact, it's barely emitting any light at all. FAST J0139+4328 appears to be what is known as a dark galaxy. Aside from a small smattering of stars, the galaxy seems to be made up almost entirely of dark matter.
https://arxiv.org/pdf/2302.02646.pdf
The article states that the "dark matter theory isn't perfect … snip … One problems is a discrepancy between simulations of the dark matter distribution in the Universe and the number of dwarf galaxies we see out there orbiting larger galaxies. There are way fewer dwarf galaxies than the simulations suggest there ought to be.” Then is suggests that maybe the missing dwarf galaxies have very few stars and consist primarily of gas and dark matter, and
Then the article mentions the previous case of a galaxy called Dragonfly 44 which in 2016 was found to be consistent with 99.99 percent dark matter. “Four years later, however, astronomers determined that Dragonfly 44 wasn't so abnormal.” So take this new *dark galaxy* with a grain of 盐.[t]o search for such a galaxy, Xu and his colleagues used the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China. They used the telescope during gaps in its observation schedule as a ‘filler’ project to conduct a search for the radio emission of large clouds of neutral atomic hydrogen (HI) gas in intergalactic space, looking for features consistent with a galaxy. And they got a hit: the radio waves emitted by a cloud of HI 94 million light-years away were consistent with a rotating disk galaxy, without the optical light expected of one. Follow-up observations in infrared and ultraviolet revealed a faint smattering of stars. … snip … According to the team's calculations, the galaxy has an upper limit of 690,000 solar masses' worth of stars – and it contains 83 million solar masses' worth of HI. The total baryonic mass of the galaxy clocks in at around 110 million solar masses. This, however, is just a drop in the bucket of the galaxy's total mass. The team was able to calculate FAST J0139+4328's rotation speed, and from that its total mass, which came in at 5.1 billion solar masses. That would mean that the galaxy is made up of around 98 percent dark matter.