The universe could be started with a Dark Big Bang

The Big Bang may have not been alone. The appearance of all the particles and radiation in the universe may have been joined by another Big Bang that flooded our universe with dark matter particles. And we may be able to detect it.

In the standard cosmological model, the early universe was a very exotic place. Perhaps the most important thing that happened in our cosmos was the inflation event that in very early times after the Big Bang sent our universe into a period of extremely rapid expansion. As inflation came to an end, the exotic quantum fields that led to this event disintegrated, transforming into streams of particles and radiation that remain today. When our universe was less than 20 minutes, those particles began to assemble in the first protons and neutrons during what we call nucleosynthesis, a pillar of modern cosmology, since the calculations at the base accurately predict the amount of hydrogen and helium in the cosmos. At this model, a new idea has posed the hypothesis that the universe could actually be started with a Big Dark Bang.

Despite the success of our primordial universe model, we do not yet understand dark matter, which is the mysterious and invisible form of matter that occupies the vast majority of the mass in the cosmos. The standard assumption in the Big Bang models is that all processes produced particles and radiation also created dark matter.

Now, a team of researchers has proposed a new idea that our eras of inflation and Big Bang nucleosynthesis were not alone, and dark matter may have evolved along a completely separate road.

In this new scenario, when inflation ended, it flooded the universe with particles and radiation but not dark matter which remained a quantum field without decaying. As the universe expanded and cooled, that remaining quantum field eventually transformed, triggering the formation of dark matter.

The advantage of this approach is that it decouples the evolution of dark matter from normal matter, so that the Big Bang nucleosynthesis can proceed as we currently understand it while dark matter would have evolved along a separate path.

This approach also opens up avenues for exploring a rich variety of theoretical models of dark matter because having a separate evolutionary track would be easier to take into account in calculations to see how it might compare with observations. For example, the team was able to determine that if there really was a so-called "Big Dark Bang," it must have happened when our universe was less than a month old. Research has also revealed that the appearance of a Dark Big Bang must have unleashed a truly unique signature of strong gravitational waves that would persist in today's universe. Current observing experiments should be able to detect these gravitational waves, if any.

We still don't know if a Dark Big Bang actually took place, but this research provides a clear pathway to verify its existence.

References: Universe Today