Algorithm imitates the intergalactic environment of the Universe

(ORDO NEWS) — The Institute of Astrophysics of the Canary Islands has led the development of a new numerical procedure for reproducing the intergalactic medium resulting from cosmological simulations of 100,000 hours of computation using big data and machine learning methods.

Through this algorithm, called Hydro-BAM, the researchers were able to exploit a hierarchy in the relationship between the properties of dark matter, ionized gas, and intergalactic neutral hydrogen, the ingredients that make up the large-scale structure of our universe.

The study accurately reproduced the so-called Lyman-alpha forests, the pattern of lines in the spectra of distant galaxies and quasars that forms when the light emitted by these objects is absorbed by clouds of hydrogen gas along its path.

The analysis of these forests is fundamental to the development of our understanding of the universe as a whole.

Current observations indicate that our universe is dominated by dark matter and dark energy, which are much more numerous than ordinary or baryonic matter.

Baryon matter makes up only 5% of the entire mass of the universe. In contrast, dark matter makes up roughly 27% of the cosmos. The remaining 68% is dark energy, which is responsible not only for the expansion of the Universe, but also for its constant acceleration.

A team from the Institute of Astrophysics of the Canary Islands, led by Francisco Shu Kitaura, and Osaka University, led by Kentaro Nagamine, have developed new strategies to recreate fast and detailed computational models of the formation and evolution of the universe.

Specifically, the team has developed a new algorithm called Hydro-BAM that combines cutting-edge concepts from probability theory, machine learning, and cosmology.

The algorithm produces accurate predictions in just a few tens of seconds, which is equivalent to more expensive hydrodynamic simulations that take about 100,000 hours on a supercomputer.

The purpose of these studies is to refine the understanding of the large-scale structure of the Universe and to obtain information about its evolution during cosmic time by modeling and observing baryon quantities.

Using this new computational procedure, the researchers considered the connection to the universe under study, putting millions of virtual observers to simulate the Lyman-alpha forest, it was investigated in the absorption of the lines of sight of quasars.

This pattern is formed when “trees” of hydrogen gas scattered throughout the universe absorb the light emitted by these distant objects.

In this way, scientists can see distinct extinction lines corresponding to clouds at different distances and therefore showing different ages of the universe, as well as providing information about the intergalactic medium.

“The breakthrough came when we realized that the relationships between the amounts of intergalactic gas, dark matter and neutral hydrogen that we were trying to model are well organized in a hierarchical way.

The ionized gas has a distribution in space, while neutral hydrogen is determined by the distribution of the ionized gas; moreover, the joint distribution of ionized gas and neutral hydrogen gives us information about the thermal state of the gas and allows us to predict the absorption flux of the Lyman-alpha forest,” the scientists explain.

Despite their success, the authors say the study is just getting started and plan to create thousands of simulated universes incorporating baryonic physics, which should allow for a comprehensive analysis of data from galactic surveys such as DESI, WEAVE-JPAS and the Subaru PFS project.


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