Dark matter may have its own invisible periodic table of elements, the key is the ``primordial black hole'' immediately after the Big Bang

Dark matter is thought to make up most of the mass in the universe, and although evidence of its existence has been found everywhere from the rotation of galaxies to

the large-scale structure of the universe , its true identity remains unknown. Unknown. A study has been published that argues that there is actually not just one type of dark matter, but that there are different types of dark matter, just like ordinary substances made of various elements.

[2310.08526] Recycled Dark Matter

Dark matter may have its own 'invisible' periodic table of elements | Live Science

Previous research has believed that dark matter is a type of light, simple particle that rarely interacts with normal matter and is universally present in the universe. Eager searches to find new particles have all ended in vain. For this reason, scientists have begun to think that ``dark matter may be rarer but heavier,'' but no model has been established that would allow such heavy particles to exist in sufficient quantities in the early universe. yeah.

In a paper published on the preprint server arXiv in October 2023, Thomas C. Gehrman of the University of Oklahoma's Department of Physics and Astronomy and his colleagues based on the hypothesis that primordial black holes existed, predicting the existence of primordial black holes in the universe immediately after the Big Bang. We announced a theory that enables the creation of dark matter particles.

According to researchers, in the early universe, the forces of nature separated from each other, and a violent phase transition occurred as the forces of nature changed from a 'unifying force' to the current '

four fundamental forces .' This phase transition was so overwhelming that it changed the underlying physics. It sounds extraordinary in words, but an experiment that used a particle accelerator to recreate the universe a few seconds after the Big Bang revealed that one of the four fundamental forces, ``electromagnetic force'' and ``weak nuclear force.'' It has been confirmed that they will merge into one.

In their research, Gehrman and his colleagues found that heavy dark matter could be trapped in such an early phase transition. If this happens, a situation will occur in which some parts of the universe will transition to the new physics, but there will still be areas that have not yet transitioned. This is just like when you boil water, bubbles of water vapor become trapped in the liquid water.

In this model, the initial dark matter is light, and the dark matter that is created later is heavy. Then, the density of the dark matter trapped inside the bubble suddenly increases, causing all the dark matter to collapse and become a primordial black hole. The black hole created in this way evaporates due to Hawking radiation , but Gehrman et al. theorize that some dark matter is ejected and revived at that time.

The following is a diagram showing the origin of the universe and dark matter proposed by the research team. First, in the early universe on the far left, a true vacuum bubble filled with heavy dark matter is formed (True vacuum DM heavy). Then, ultraheavy dark matter (UHDM) is emitted by Hawking radiation from the primordial black hole (PBH). Gehrman et al.'s hypothesis is that in this way, cold superheavy dark matter remained in the current universe.

When a black hole evaporates, several types of dark matter particles are produced. These particles share many characteristics, such as their invisibility, but differ in their mass, speed, and interactions with ordinary matter. Therefore, this model suggests that, just as ordinary matter has a periodic table of elements, dark matter has multiple types of particles, and that they are interacting in complex invisible interactions throughout the universe.

Although this theory is still a hypothetical concept and will not be confirmed by experiments or observations, astronomers are using the observation of gravitational waves from the Big Bang to directly determine when the universe began. I'm looking for a way to observe it.

in Science, Posted by log1l_ks