Astronomers have identified the universe’s unaccounted-for ordinary matter within the tenuous gas that threadless fills intergalactic space. By scrutinizing the signals emitted by Fast Radio Bursts (FRBs), astronomers verified that the matter is located within the Warm-Hot Intergalactic Medium (WHIM).

Highlights:

• Fast Radio Bursts serve as probes for the intergalactic medium.
• FRB signal analysis detected the universe's missing baryonic matter.
• This missing baryonic matter exists within the hot, diffuse WHIM.
• The findings confirm Big Bang predictions about baryonic matter distribution.
• Precise measurements of multiple FRBs enabled this detection.

Because Fast Radio Bursts travel through the cosmic distances, they shall penetrate through the thin plasma between the galaxies. This interaction reduces the various wavelengths in the burst signal at a slight pace. Astronomers located the classic signature of the WHIM of the baryonic matter by exactly quantifying the dispersion effect on many FRBs.

A well known fact to scientists is that observed baryonic matter in stars and galaxies is significantly lower than the total value estimated by the Big Bang. That part that could not be observed was the so-called missing baryon problem. The research by FRB gives conclusive evidence that the missing baryonic matter exists in the diffuse WHIM and contributes the corresponding amount.

The finding illustrates the potential of Fast Radio Bursts as a tracing mechanism of the matter in the lowest density areas of the universe. With the puzzle of missing baryonic matter, a big hole in our knowledge about the cosmic structure was closed.