Axisions proved to be the best candidates for the role of components of dark matter

Axisions proved to be the best candidates for the role of components of dark matter

Improved simulations by researchers at the Berkeley Laboratory have made it possible to estimate the mass of axions more accurately. These axions, formed less than one billionth of a second after the Big Bang, can be the best candidates for being part of a mysterious dark matter that we don't know yet.

Dark matter accounts for most of the matter in the universe, about 85%, but we still don't know what it is. So far, its search has focused on massive, compact objects in our galaxy and other galaxies, in thinly interacting massive particles. None of them has shown themselves as a possible candidate.

Researchers suspect that dark matter is composed of particles we don't yet know about, and in a study published today in the magazine , physicists from Lawrence Berkeley National Laboratory, in collaboration with scientists from the Massachusetts Institute of Technology, have concluded that these particles may be axions.

Using new computing techniques and Cory, one of the world's largest supercomputers, Professor Berkeley Benjamin Safdy and his colleagues at the Massachusetts Institute of Technology have modeled an era in which axions could be obtained. It begins with a billion-dollar fraction of a second after the Big Bang that created the universe in which we live. Created in large quantities during the Big Bang, axion particles still have to be found somehow in space.

So there is a question that has already been raised in the past, to which Safdy's modelling and his colleagues today point: what if the axions were part of dark matter?

Axion was proposed in 1978 as a new elemental particle that could explain why neutron's back does not precede or oscillate in the electric field.

Since the 1980s, physicists have seen axion as a candidate for dark matter, and the first attempts to detect axions have begun. First, using the Standard Model equations, you can calculate the exact mass of axion. However, the equations are so complex that so far we have only inaccurate estimates. As a result, experiments based on complex radio receivers called microwave resonators have to adjust to millions of frequency channels to try to find the one that corresponds to the mass of axion.

The most accurate estimate of axion mass to date

Modelling now at the National Research and Computing Centre

A very small estimation of the mass of axions certainly does not detect axions in the microwave resonant chamber, which is the most common experiment in their detection. This approach, of course, will not detect them. In this connection, Safdy explains:

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Modeling on Kori's supercomputer

Safdy and his team approached colleagues at the Massachusetts Institute of Technology and Berkeley Labs to make even more accurate simulations using new methods of calculation. During the simulation, a small part of the expanding universe appears to be a three-dimensional grid where equations are solved. This grid becomes more detailed around areas of interest. Thus, it concentrates computing power on the most important parts of the simulation.

This technique allowed Safdy to see thousands of times more details around the areas where axions are generated. As a result, the total number of axions produced can be more accurately determined. And then, given the total mass of dark matter in the universe, the mass of axions is released.

Swimming axions in the early universe

Modelling showed that the vortex is formed after the first billionth of a second after the Big Bang, a kind of string made of axions, which undergo many violent dynamics in the expansion of the universe.

"," explains Safdy." By tracking the number of axions destroyed, researchers can predict how much dark matter was created.

New simulations and pilot studies in the future

The team is now working with a new supercomputer cluster under construction at the Berkeley Laboratory, which will allow simulations that allow even more accurate mass determination. The new generation's supercomputer quadruples the computational power of NERSC.

"," says Safdy." Indeed, as soon as modelling gives even more precise mass, the axion may be easier to find and be confirmed or not as a mysterious component of dark matter.