Fast-radio bursts (FRBs) are powerful emissions of radio waves lasting only a fraction of a second. Their origin is still a complete mystery but astronomers are using these events to learn more about intergalactic space.
An international team of researchers jointly led by Vikram Ravi from Caltech and Ryan Shannon from Curtin University has observed FRB 150807, the most luminous FRB to date, and used its light to establish how matter is distributed between galaxies.
According to the research published in Science, this intergalactic gas is no more turbulent than the theorists were expecting it to be.
“It's nice to know that theories that have predicted such weak turbulence are not wrong, and our turbulence measurements are consistent with the upper end of these predictions,” Ravi told IFLScience.
“FRBs provide really the only useful way of probing turbulence in intergalactic matter along a variety of sightlines, and our result shows that this is possible.”
About half of the visible matter is believed to be spread out between galaxies and it’s usually too diffused to be visible with a normal telescope. This matter is in a magnetized plasma state and the radio waves from the FRBs are affected by the density of the plasma and how it moves.
“However, if you don't know how much plasma there is, you can't back out a measure of the magnetic field strength,” added Ravi.
“FRBs provide an accurate measure of the amount of plasma by their dispersion, which is the delaying of the light at different wavelengths by different amounts (like the effect that causes rainbows).”
These “radio-rainbows” have allowed the team to work out the magnetic field towards FRB 150807. There have been only a dozen recorded FRBs and given that this method measures only one direction of the intergalactic magnetic field it is clear that there is a lot more to do in this field.
FRBs are believed to be produced by highly magnetized young neutron stars but recent findings have caused havoc for that picture. Even this finding casts a doubt as it shows not much magnetic alteration near the source.
Soon, new radio telescopes could provide many more detections of FRBs. Astronomers think that there are between 2,000 and 10,000 FRBs every day and about 10 percent might be as bright as FRB 150807. New observation could provide some insight into their origin, which remains very much unclear.