Astrophysics at the University of California conducted a study simulating the formation of small galaxies after the Big Bang, which for the first time studied interactions between gas and dark matter that had not been previously observed. The researchers found that galaxies appear to be far smaller, but much brighter, and form much faster than typical simulations that ignore these interactions predict.
Spherical galaxies cover the entire universe and are considered the oldest type of galaxies. They represent special interest for scientists investigating the origin of the universe. However many of them do not correspond to what they expected to find. For example, galaxies near the Milky Way rotate faster or have less dense structures than models predict. This indicates that simulations may not take into account the interaction between gas and dark matter.
The new study improved modeling, taking into account interactions between dark matter and gas, and showed that these dwarf galaxies were likely much brighter than expected in the early stages of the Universe’s formation.
The authors of the research propose to find such bright small galaxies with the help of the telescope «James Webb». If only faint galaxies are found, it could mean that some ideas about dark matter will have to be reconsidered.
Dark matter, which does not interact with electromagnetism or light, plays an important role in the formation of galaxies. Its presence can be established only through gravitational influence on ordinary matter. It is estimated that about 84% of the matter in the Universe is dark matter, but it has not been directly detected.
All galaxies are covered in clouds of dark matter, which is believed to be necessary for their formation. The standard cosmological model, used by astrophysicists, explains how clumps of dark matter in the early Universe attracted ordinary matter through gravity, leading to the formation of stars and galaxies. However, most of the particles in dark matter move much slower than the speed of light, so this accumulation process must have occurred gradually.
More than 13 billion years ago, before the first galaxies formed, gas flowed quickly past slowly moving dark matter, which should have attracted it and facilitated the formation of galaxies.
«In models that do not take into account flow interaction, this is what happens. The gas is gravitationally attracted to the dark matter and forms clumps, dense enough to synthesize hydrogen, which in turn leads to the formation of stars, like our Sun, — explains Claire Williams, lead author of the article and graduate student at the University of California.
However, Claire Williams and her colleagues discovered that when considering streaming interactions between dark matter and gas, the gas was removed from the dark matter and could not immediately form stars. After just millions of years, gas returned to the galaxy, and the process of star formation accelerated. As a result, these smaller galaxies formed more young, hotter and brighter stars, so they shone much brighter.
The research provides new scientific insights into the process of formation of small galaxies after the Big Bang and allows us to better understand the role of dark matter in this process. Further research and discovery of such bright small galaxies will help to clarify the idea of dark matter and its role in the evolution of the Universe.