Fast Radio Burst Galaxy Identified - Missing Matter Found

FRB Dispersion

Recently in the news it was reported that for the first time the location of a Fast Radio Burst (FRB) had been identified. This was done by coordinating observations with several other observatories around the world. The result was a determination that the source was about 6 billion light years away.

Knowing the distance of the FRB source has allowed researchers to do some calculations such as red shift due to Hubble expansion (confirming already determined values) and dispersion due to matter in the path of the signal (essentially determining the density of the Universe).

I'll let the article explain further, but this is a significant result. Essentially it's saying that all the normal matter, as predicted by modern cosmological models, is accounted for. Here is the section of the article that provides the relevant details:

Discovery of a fast radio burst reveals 'missing matter' in the universe

.... "It's the first time we've been able to identify the host galaxy of an FRB" adds Evan Keane. The optical observation also gave them the redshift measurement (the speed at which the galaxy is moving away from us due to the accelerated expansion of the Universe), the first time a distance has been determined for an FRB. For understanding the physics of such events it is important to know basic properties like the exact position, the distance of the source and whether it will be repeated. "Our analysis leads us to conclude that this new radio burst is not a repeater, but resulting from a cataclysmic event in that distant galaxy," states Michael Kramer from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, Germany who analysed the radio profile's structure of the event. MPIfR's Effelsberg Radio Telescope was also used for radio follow up observations after the alert.

FRBs show a frequency-dependent dispersion , a delay in the radio signal caused by how much material it has gone through. "Until now, the dispersion measure is all we had. By also having a distance we can now measure how dense the material is between the point of origin and Earth, and compare that with the current model of the distribution of matter in the Universe" explains Simon Johnston, co-author of the study, from CSIRO's Astronomy and Space Science division. "Essentially this lets us weigh the Universe, or at least the normal matter it contains."

In the current model, the Universe is believed to be made of 70% dark energy, 25% dark matter and 5% 'ordinary' matter, the matter that makes everything we see. However, through observations of stars, galaxies and hydrogen, astronomers have only been able to account for about half of the ordinary matter, the rest could not be seen directly and so has been referred to as 'missing'. "The good news is our observations and the model match, we have found the missing matter" explains Evan Keane. "It's the first time a fast radio burst has been used to conduct a cosmological measurement." "This shows the potential for FRBs as new tools for cosmology," concludes Michael Kramer who also worked on the calculation to weigh the missing matter. "Just think what we can do when we have discovered hundreds of these."....

The entire article can be found here