A collision between some of the largest structures in space has given us a clue about where the missing matter is.
In the Abell 98 cluster, where two sub-clusters are in the process of merging, scientists have found a warm-hot intergalactic medium.
One of the leading candidates for the location of a shortfall in the amount of visible, garden-variety particles called 'baryonic matter' measured in the local Universe is this fog of plasma.
The WHIM is out there, but it's hard to argue how it contributes to the missing baryons.
The Harvard-Smithsonian Center for Astrophysics (CfA) says finding the missing matter has been extremely difficult. We're excited that we've found another one.
One of the strangest questions we have about the universe is the missing matter. The distribution of matter/energy throughout the universe is known. We don't know what it is because it's mostly dark energy and dark matter.
The rest is baryonic matter. Everything we see is made from the stuff that we can detect.
The Cosmic Microwave Background (CMB) that scientists have been able to decode shows how much baryonic matter was around at the time of the big bang.
The numbers didn't add up when scientists began to look at the baryonic matter. Between half and a third of what has been predicted has not been found.
The WHIM is a type of gas with a temperature between 10,000 and 10 millionKelvin. It has been difficult to locate these tenuous structures in the space between bright galaxies.
Abell 98 is a cluster of galaxies that is over a billion light years away. There are hot gas structures between the sub-clusters. A giant shock wave can be seen as the sub-clusters come together.
The properties of the gas were probed and they found two different temperature regimes. The hotter gas may be the result of gas haloes around the two sub-clusters.
The cooler gas is consistent with the hotter end of the WHIM range.
There is more evidence for WHIM on the far side of the sub-cluster than in the space between the two clusters. This was also consistent with WHIM.
The researchers write in the paper that the measurement shows that there is a larger-scale structure with the diffuse WHIM connecting to the cluster outside.
We don't have enough WHIM to account for all the bars that are missing. It's possible that it's hiding in other places, or that it's hiding as thin gas in the universe.
New- generation X-ray telescopes are helping us detect WHIM. When they look into the voids between the stars, they should be able to see more of the deep space secrets.
Both papers are available on arXiv. You can find them here and here.
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