Galaxies and Dark Matter: Is It Possible for Galaxies to Form Without It?

As of the current state of scientific knowledge, there is no definitive evidence of a galaxy that contains no dark matter. Dark matter is a hypothetical form of matter that is thought to make up approximately 85% of the matter in the universe. This article explores the ongoing debate and the role of dark matter in galaxy formation, while delving into the latest research and theoretical models.

Introduction to Dark Matter

The existence of dark matter is inferred from its gravitational effects on visible matter such as stars and galaxies. While its direct detection remains elusive, the evidence for its existence is robust and multifaceted. Some of the most compelling evidence comes from the observed motions of galaxies, gravitational lensing, and the cosmic microwave background radiation.

The Case of NGC 1052-DF2

The discovery of galaxies without apparent dark matter has received significant attention. One notable example is the galaxy NGC 1052-DF2, which was first observed in 2018 and initially appeared to have no detectable dark matter. However, subsequent studies have suggested that it may contain a small amount of dark matter, although in quantities much lower than usual.

Role of Dark Matter in Galaxy Formation

Dark matter is thought to play a crucial role in galaxy formation, particularly in the process of hierarchical clustering, where small structures merge to form larger entities. Computer simulations that include dark matter closely resemble observed galaxies, whereas those that do not include dark matter fail to produce realistic galaxies.

Theoretical Evidence

One of the most convincing pieces of evidence for the existence of dark matter comes from the observation of rotational curves of galaxies. The rotation curve of a galaxy describes how the orbital velocity of stars and gas varies with distance from the center. Without dark matter, the rotational velocity would drop off rapidly with distance from the center. However, observations show that most galaxies have relatively flat rotation curves, suggesting the presence of additional gravitational mass, which is attributed to dark matter.

Current Observations and Simulations

Current observations and theoretical models strongly suggest that dark matter is an essential component of galaxies. Theoretical simulations that incorporate dark matter produce galaxies with properties that closely match those of real galaxies, while simulations that do not include dark matter fail to produce realistic galaxies.

Conclusion

While it is theoretically possible for a galaxy to contain very little dark matter, the current evidence and simulations strongly indicate that dark matter plays a vital role in galaxy formation. The absence of significant dark matter in galaxies would likely lead to unrealistic and unproductive outcomes in simulations and observations.