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

A composite image showing the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 52. The blue areas show regions with the most mass; dark matter makes up most of this mass.
A composite image showing the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 52. The blue areas show regions with the most mass; dark matter makes up most of this mass. (Image credit: NASA, ESA, CFHT, CXO, M.J. Jee (University of California, Davis), and A. Mahdavi (San Francisco State University))

The universe may have produced dark matter in the first few minutes of the Big Bang, according to new research. Those particles then got trapped into ultradense pockets. Some of those pockets splintered off to become black holes, which then dissolved into a shower of multiple dark matter particle "species," creating a "dark matter periodic table" of invisible elements, the study authors suggest.

Physicists still struggle to explain dark matter — the mysterious, invisible form of matter that makes up the vast majority of the universe's mass. While cosmologists and astronomers have identified circumstantial evidence for the existence of dark matter, from the rotation rates of stars within galaxies to the largest structures visible in the cosmos, they have not identified exactly what the dark matter is.

The paper noted that the early universe underwent severe phase transitions as the forces of nature split off from each other, going from a single unified force into the four fundamental forces of today. At each transition, the underlying physics changed. This isn't as wild as it sounds, as scientists can reproduce the last of these transitions in particle accelerators: At high enough energies, recreating the first few seconds of the Big Bang, we can observe the electromagnetic and weak nuclear forces merging into one.

In their model, the earliest dark matter was light but dark matter from later periods was heavy. In this scenario, dark matter gets trapped inside the bubbles, where the densities skyrocket to the point where all the dark matter collapses and forms black holes. Those black holes soon evaporate via Hawking radiation — in which radiation slowly "leaks" out of black holes in the form of thermal energy — well before the appearance of normal matter.

But as the black holes evaporate, dark matter makes a comeback, as the black holes spit out new dark matter particles before they die, the team's model showed. This clever mechanism limits the total amount of massive dark matter in the universe, because only so much can escape the black holes before they evaporate completely.

Experimental evidence for this idea is still a long ways away, as it is right now a deeply hypothetical concept. Direct detection of one or more dark matter particle species would certainly bolster the idea. And astronomers are currently developing ways to observe gravitational waves from the big bang, which would give us direct observational access to this critical epoch in the history of the universe.

There could be all sorts of new interactions among these dark matter species, leading to a complex web of physics acting invisibly throughout the universe.

Paul Sutter
Astrophysicist

Paul M. Sutter is a research professor in astrophysics at  SUNY Stony Brook University and the Flatiron Institute in New York City. He regularly appears on TV and podcasts, including  "Ask a Spaceman." He is the author of two books, "Your Place in the Universe" and "How to Die in Space," and is a regular contributor to Space.com, Live Science, and more. Paul received his PhD in Physics from the University of Illinois at Urbana-Champaign in 2011, and spent three years at the Paris Institute of Astrophysics, followed by a research fellowship in Trieste, Italy.