Mysterious Fast Radio Bursts

The radio telescope near Penticton has detected signals that were sent from some mysterious object billions of light years away, at a time when the Earth was so hot that water boiled on its surface and the atmosphere so toxic that life couldn’t exist.

Dominion Radio Astrophysical Observatory near Penticton. Image: Phys.org

No one knows what the objects are but the bursts are strong and short. I asked Paul Scholz, Research Associate at the Dominion Radio Astrophysical Observatory in Penticton what they might be: Cosmic strings, Neutron stars, Supernovae, evaporation of black holes? His reply by email:

“This is what we hope to answer!”

Maybe the radio bursts are alien signals sent long ago to arrive at a time when we have the technology to detect them? Deborah Good, a UBC PhD student working on the project, is doubtful:

“There’s a bunch of theories right now, but one thing we’re really confident about is that it’s not aliens,” she told the Globe and Mail (August 5, 2018).”

The discovery of these signals is so new that they don’t even have a name other than the descriptive “Fast Radio Bursts.” I previously read about FRBs in Scientific American and I wondered if the Penticton observatory called them anything else, such as “Lorimer bursts?”   Dr. Scholz relied:

“We call them FRBs. Lorimer burst refers to FRB 010125, the first FRB that was discovered by Duncan Lorimer in 2007.”

The article in Scientific American was written by the same Professor Lorimer, the discoverer of FRBs. He was originally perplexed by his discovery and wondered if they were even real:

“We theorized that if we could identify and understand them, we could not only learn about a new type of cosmic event, but we could also estimate their distances through dispersion measurements and use them to do something as grand as map out the large-scale structure of the universe. But first we had to prove that the burst was real –a quest that would take many surprising turns and almost end in retreat. (April, 2018).”

What intrigues me about this discovery is this use of “dispersion measurements” to measure astronomical distances. Before researching this article, I was only familiar with the “red shift” method: as objects recede from us, the colour they emit is shifted towards the red end of the spectrum. The greater the shift, the greater the distance.

Dispersion measurements (DMs) depend on the effect that clouds of electrons have on the radio signal.  As the signal streams towards us, its frequencies are stretched out; dispersed. The greater the DM, the greater the distance. Approximately.

A slight error in the measurement is caused by the fact that electrons are not evenly distributed in space. While the measurement is not precise, it’s pretty good.

The Penticton observatory is collaborating with other telescopes to determine the size and location of the sources of FRBs.

The sources appear to be very small and very powerful says Lorimer. They are only one-five hundredth the diameter of the sun, yet give off as much energy in one second as the sun does in a month.

It will be fascinating to find out what these explosive bursts are. I’m quite sure little green men didn’t send them.

 

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