Simulation helps understand the “dark universe” and the emergence of primordial galaxies

(ORDO NEWS) — Visible matter makes up only 16 percent of the total mass of the universe. Little is known about the nature of the rest of the mass, called “dark matter”. Even more surprising is the fact that the total mass of the universe corresponds to only 30 percent of its energy. The rest falls on dark energy, the properties of which are unknown to scientists, but which is responsible for the accelerated expansion of the Universe.

Astrophysicists use large-scale sky surveys or conduct detailed studies of the properties of galaxies to find out new details about dark matter and dark energy. But scientists can only correctly interpret the results of these observations if they compare them with predictions made on the basis of theoretical models of dark matter and dark energy. However, these simulations require tens of millions of hours of computer time, even on modern supercomputers.

The Extreme-Horizon collaboration was able to run simulations of the evolution of cosmic structures from the early days after the Big Bang to the present, using the Joliot-Curie supercomputer capable of 22 * ​​10 ^ 15 floating point operations per second.

The first result of the modeling was an adjustment to the Lyman-Alpha Forest lines. The Lyman-Alpha Forest is a family of hydrogen emission lines related to different hydrogen clouds located at different distances on a cosmological scale. Since with an increase in the distance to the hydrogen cloud, the wavelength of its radiation, or redshift, increases, Lyman-Alpha Forest corresponds to a series of hydrogen clouds located at different redshifts sequentially in order of distance from us. Correction of these lines is necessary due to the fact that when passing by other bright sources on the way to Earth, the radiation of the hydrogen cloud inevitably undergoes changes. With the use of the DESI (Dark Energy Spectroscopic Instrument) observatory under construction, such changes will cause a bias in the estimate of cosmological parameters,

Another interesting conclusion from the simulation was the discovery of the “hive” mechanism of galaxy formation. When the universe was between 2 and 3 billion years old, a number of atypical, ultra-compact massive galaxies formed rapidly from a large number of tiny galaxies, the researchers found.

The work was published in the Monthly Notices of the Royal Astronomical Society; lead author Solène Chabanier.

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