It is known that in the first few nanoseconds after the Big Bang a huge amount of matter and energy emerged in the Universe. This generated matter, heated to thousands of trillions of degrees, began to fly away from the place of the explosion in all directions almost at the speed of light. And over the next few hundred million years the temperature in the Universe dropped so much that the formation of elementary particles, not just the existence of quarks and photons of light, became possible. It was during this time that hydrogen and helium atoms began to form, this process absorbed almost all photons of light, and the so-called “dark ages” began, for the stars that illuminate the space of the universe did not yet exist.
Eventually, vast clouds of cosmic gases gained density sufficient for “self-combustion” of thermonuclear reactions, thanks to which the first rays of light penetrated the space and the period of so-called reionization began. It was thanks to the process of reionization that the first heavier elements appeared in the Universe, formed in the bowels of clouds of ionized plasma, which, in turn, were formed under the influence of light from the first stars.
It is only natural that this turbulent period of the Universe’s existence is the subject of intense scientific interest, but unfortunately it is very, very difficult to study it through astronomical observations, so here mathematical modeling comes to the rescue. And researchers at the Massachusetts Institute of Technology (MIT) have recently completed calculations on a new model that is the largest and most detailed such model to date.
Thesan model, named after the Etruscan goddess of dawn, covers the entire period of reionization, taking into account the interaction between different types of gases, the effects of gravity and various kinds of radiation. The volume of simulated space is 100 million cubic years, and the time frame of simulation starts from the point of 400 thousand years and ends at the point 1 billion years after the Big Bang.
Among other things, the Thesan model has greater resolution than other models, thanks to the use of a new algorithm that tracks the interaction of light with cosmic gas, the behavior of cosmic dust clouds and the emergence of the first individual galaxies.
Thesan was calculated using the SuperMUC-NG supercomputer in Garching, Germany. The system’s 60,000 computing cores have logged a total of 30 million hours and performed all the necessary calculations, in the results of which the scientists have already found some surprising things.
“Thesan simulations showed that light could not propagate over long distances in the early Universe,” the researchers wrote, “At the beginning of the reionization process, this distance was extremely small, and over the next few hundred million years, the propagation distance of light increased tenfold.”
Thus, scientists have found that light at the end of the era of pereionization could propagate greater distances than previously thought. It was also noted that the course of the process of pereionization began to have a huge impact on the first galaxies of different masses and types that emerged. By the way, this last hypothesis can be confirmed by real astronomical observations and this scientists plan to do in the near future.
