https://www.vice.com/en_us/article/7kv33g/a-common-feature-of-galaxies-is-challenging-what-we-know-about-the-universe

It’s a natural human instinct to want to understand our cosmic surroundings, but the universe doesn’t always (or even often) make it easy. For instance, scientists have spent decades building a standard model of cosmology that explains much of the weird phenomena that we see in space, yet many outlier observations still challenge this established framework.

One example can be found in barred galaxies, which are extremely common spiral galaxies that are named after the radiant bars of stars running through their central regions. According to the standard model, the rotation of these bars should be slowed down over time by the friction caused by cold dark matter haloes, which are immense hypothetical structures that envelop galaxies.