Computer simulation of the distribution of matter in space. In the orange areas are galaxies, and blue - gas and dark matter. A study by the University of California showed that the opaque areas resemble large voids in the galactic distribution, because too little light from the galaxies can reach those regions and make them transparent.
California astronomers have solved the mystery of the early universe and its first galaxies. Scientists knew that more than 12 billion years ago, about 1 billion years after the Big Bang, gas in deep space was more opaque than it is now, in some areas. And this opacity varied greatly from place to place. But there was no certainty about what caused these changes.
To solve the mystery, the researchers used one of the world's largest Subaru telescopes on Mauna Kea (Hawaii) to search for galaxies of young stars in space with 500 million light years, where the intergalactic gas is extremely opaque. If there were an unusually small number of galaxies in the region, one could understand that starlight could not penetrate the intergalactic gas. If there are too many of them, then the region has cooled significantly over the previous few hundred millions of years. These are competing models and both were convincing. It turned out that the region contains far fewer galaxies than expected, which means that the starlight could not pass. But opacity is not the cause of the absence of galaxies. All the way around! Since gas in deep space remains transparent due to galactic UV light, fewer nearby galaxies can make it darker.
In the first billions of years after the Big Bang, UV light from the first galaxies filled space with gas in deep space. Conclusions suggest that this would happen earlier in areas with a large number of galaxies. Astronomers plan to continue exploring whether the void will reveal other similar clues about how the first generations of galaxies illuminated the Universe during the early period.
