CHARBONNEAU – Fast Radio Bursts: closer to identifying but still mysterious

THEY’RE CALLED Fast Radio Bursts (FRBs) simply because they are fast: they last only a few thousandths of a second and because they are radio waves: they are part of electromagnetic spectrum around 1 Gigahertz.

That’s about it.

However, there are a few more clues to their origins since first being discovered — somewhat by chance — by Prof. Duncan Lorimer. In 2007 he gave an assignment to his student to search through archival data recorded in 2001 by a radio dish in Australia.

It would have been a tedious assignment, pouring over old data. But it paid off and now the Lorimer Burst FRB 010724 is famous for being the first Fast Radio Burst.

FRBs are remarkable because of their incredible energy. A burst of a few thousandths of a second produces as much energy as the sun does in a month.

They are also a glimpse back in time. Energy from FRBs was sent from mysterious distant explosions 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.

I first wrote about FRBs in 2018. Back then, I asked Paul Scholz, Research Associate at the Dominion Radio Astrophysical Observatory near Penticton what they might be: Cosmic strings, Neutron stars, Supernovae, evaporation of black holes?  His terse reply:

“This is what we hope to answer!”

We now know that these explosions happen at least 800 times a day all over the sky, and they are one of the most exciting topics in astrophysics. Although much about FRBs remains unknown, in just the past year a clearer picture has emerged.

“I think we’re closer to understanding what some FRBs are,” says Ziggy Pleunis, an astrophysicist at the University of Toronto.

“But as we’ve been going on this quest, new discoveries have led to new questions (Scientific American, June, 2022).”

It looks like some of them come from magnetars. Research teams detected an enormous blast of radio energy coming from our neighbourhood; a magnetar located in our Milky Way.

Magnetars are an extreme kind of neutron star, a city-sized remnant left behind when a massive star dies in a supernova. A magnetar’s magnetic field can be so strong that approaching within 1,000 kilometers of one would disrupt your body’s atomic nuclei and electrons, causing you to effectively dissolve.

Magnetars are not the whole story, however. Because FRBs vary in brightness, duration and other properties, it is unlikely that any single observation can explain them all.

The radio telescope at Dominion Radio Astrophysical Observatory that was being upgraded in 2018 to detect FRBs is now complete and making progress. In its first year of operation in 2021, the radio telescope released a catalog of 536 FRBs, quadrupling the number known.

The bursts come in two distinct flavours — those that repeatedly flash their signals and those that are one-off events.

Given recent history, more FRB excitement is likely in the coming years, Prof. Lorimer says: “Just when you think things are settling down, you have a year with all these remarkable discoveries.”

David Charbonneau is a retired TRU electronics instructor who hosts a blog at http://www.eyeviewkamloops.wordpress.com.