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.

Previous work assumed that dark matter was simple: a single kind of extremely lightweight particle, flooding the universe, that hardly ever interacted with normal matter. But intense searches for new such particles have come up empty. That led cosmologists to wonder if the dark matter particles might be much rarer, but also much heavier. However, theoretical physicists have struggled to find models that would seed the early universe with the right number of such heavy particles.

In the new study, published in October in the preprint database arXiv, a team of cosmologists found a way to generate massive dark matter particles soon after the Big Bang. The trick was to sprinkle in black holes.

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.

The researchers found that ultraheavy dark matter could get trapped during one of these early-universe phase transitions. If the transition was messy, it would trigger the formation of bubbles, where some pockets of the universe had transitioned to the new physics while the rest had not yet made the change (like water boiling, with the gas phase of water trapped in bubbles surrounded by liquid).

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.

This evaporation process also generates a slew of dark matter particle species. While all of the dark matter particles share many characteristics (such as likely near-total invisibility), they would differ in their masses, speeds, and ways of interacting with normal matter. In this model, dark matter is a vast collection of different kinds of particles, much like normal matter is composed of the entire periodic table of the elements.

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

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. 

  • Jim Whitehead
    A simpler explanation: Priomiordial black holes that evaporate do not require new physics. Instead of one big pop, could the "Big Bang" be several nearby pops, like ripples of water spreading from multiple raindrops? When their giant gravitational waves collide, you will get positively reinforced clusters of mini primordial black holes arranged in complex ring shapes. The smaller black holes pop fast, lighting up the proto-galaxies, but Jupiter-sized holes (with an event horizon like a basketball) can hang around to the present as so-called dark matter haloes.
  • LaraK
    This absolutely reeks of supersymmetry simpism
  • Backofbeyond
    If so, what effect does this 26% of invisible elements have on the 5% visible matter what scientists base their simulations, theories and understanding on, not forgetting what effect the 69% Dark Energy may also have? These 3 identified areas must all work in unison, but we know only of what one of them does.
  • smaricic
    I am not a scientist, and here is my latest theory of gravity:

    Gravitational waves emanating from every atom sometimes add to each other, and sometimes subtract from each other -- just as all types of waves do. The result is that the attractive force of gravity sometimes increases and sometimes decreases.

    Inside each galaxy, the tendency is for gravity to increase; outside of each galaxy, the tendency is for gravity to decrease.

    There is no dark matter holding galaxies together; there is no dark energy forcing each galaxy away from its neighbors.

    If the above is true, how does each atom keep pumping out gravitational energy? Well, all atoms take in electromagnetic radiation from the stars. Possibly, each atom converts some small part of that "positive" electromagnetic energy into the "negative" energy of gravitational waves. Analogies don't always work, and this one might not, but I think of waves coming into a beach, and undertow pulling one swimmer out -- they call that "rip current"; but fifty yards to the north, a return current pulls another swimmer in.
  • Debed
    Can’t it just be the effect of the quantum foam bubble we are in. Hills and valleys creates gravitational effects.