New research suggests that if dark matter is made up of “dark photons,” they would not have heated the early cosmos the way scientists imagined. If this discovery is confirmed, it could mean a paradigm shift in the search for the most mysterious substance in the universe.

Dark matter remains an enigma because, although it is five times more abundant than the ordinary matter that forms stars, planets and our bodies, it is practically invisible. This is because it does not interact with light. The lack of interaction with light, unlike electrons, protons and neutrons that do, has driven the search for particles beyond the Standard Model of particle physics, resulting in several hypothetical candidates for dark matter.

Among these candidates is the dark photon, which would be the dark universe’s version of a photon capable of carrying a force other than electromagnetism, which is the function of conventional photons.

More on this story: Dark photons did not heat the early universe, study indicates

In the past, the prevailing theory among scientists was that dark photons would transform into ordinary photons while still in the hot, dense plasma that filled the early cosmos. This process would result in even greater heating of this already scalding plasma and leave detectable traces of dark photons.

Such a scenario strictly limited the search parameters for the existence of dark photons, to the point that many cosmological observations ruled out their presence.

However, new computer simulations indicate that the rejection of dark photons may have been somewhat hasty. The conversion of dark photons to ordinary photons would have ceased before significant warming could occur.

This new understanding brings search parameters back into the game that had previously been excluded.

“These exclusions suggested that the strength of dark matter should be 10^8 times weaker than it actually can be,” said Anson Hook, a member of the research team at the University of Maryland. He added that “this article opens up many new possibilities for searching for dark matter.”

Full coverage: Latest News (EN)

The team behind this investigation began to notice signs that the transformation of dark photons into photons may not be as straightforward as previously assumed, when they realized that the amount of energy involved was suspiciously large. The problem, they began to suspect, was that this process had been considered linear; that is, the energy released would gradually and steadily convert into plasma.

“The treatment in the last 15 years is a linear treatment. If you use this approximation, you can calculate the amount of energy transfer, and it is very large,” said Junwu Huang, a member of the Perimeter Institute team. He acknowledged: “And I realized that it’s not possible.”

When carrying out their first computer simulations, Huang and his colleagues found that the linear process did not offer a complete representation of the situation.

“What we realized is that when converting energy into the Standard Model plasma, the plasma actually goes crazy,” Huang said. “There are a lot of nonlinearities in the system, and these nonlinearities basically stop energy conversion after a small amount of energy is converted.”

The research represents a significant expansion of the parameters in which dark photons could exist, greatly expanding this metaphorical “hunting ground.” Furthermore, it may have implications for the search for hypothetical particles that go beyond the Standard Model of particle physics.

“By calculating plasma from the early universe correctly, experiments will probe new parameter spaces and potentially actually see something,” said Mohamad Shalaby, also a member of the Perimeter Institute team.