FRBs Ring the CHIME

Before I begin, I must correct a mistake from my article of two weeks past.  I mentioned gravity as part of the standard model of physics. It is not. The standard model omits gravity because of contradictions arising when gravity (general relativity) is combined with quantum mechanics.  I suppose the lack of a recognized particle associated with gravity keeps it out of the standard model too.

This week I’ll talk again about FRBs, or Fast Radio Bursts.  I did an update in February, but FRBs have become the darling of Radio Telescope Astronomy’s cosmic sleuths.

FRBs are transient (from less than a millisecond to a few milliseconds) radio wavelength pulses.  They appear to be coming from very energetic and as yet unidentified astrophysical processes.  Some estimates claim they exhibit in milliseconds the amount of energy our Sun puts out in a few days!

While the first one was detected on July 24, 2001, by the Parkes Radio Telescope in Australia, it wasn’t recognized until 2007 when West Virginia University astronomers spotted it the observatory’s archived data. What a find!

Since then, only a smattering of FRBs (140) had been detected.  Then came the Canadians!

At the June 9, 2021, virtual meeting of the American Astronomical Society a team of Canadian researchers reported an astonishing 535 FRBs.  How did they do it?

FRBs rang their CHIME.

CHIME is the Canadian Hydrogen Intensity Mapping Experiment, located in British Colombia.  It’s unusual looking for a radio telescope – with four 20 meters by 100 meters half-cylinder radio antennas (think snowboarding halfpipe), laid side by side on the ground.  It does not move like the traditional dish shaped antenna, so it “reads” signals as Earth rotates under the heavens.  Tuned to hydrogen’s 400-800 MHz frequency range, its 1024 receivers are suspended in sweet spots within the open cylinders. Radio noise is filtered out using cellphone technology…I KNEW cellphones had a redeeming quality!

The primary reason for CHIME’s existence, however, is to accurately measure our universe’s expansion acceleration rate.  This could lead to an understanding of dark energy.  CHIME’s FRB data is a bonus, and it certainly appears a sensitive FRB catcher. Based on its first year of operation, astronomers estimate around 800 FRBs occur every 24 hours!  An interesting result from data collected so far is that repeating FRBs tend to be several milliseconds each whereas single or one-off FRBs tend to last a millisecond or less.  Astronomers think they represent two ends of the FRB spectrum and possibly two different astrophysical phenomena.

What causes FRBs?  The jury is still out but current data suggest one source might be Magnetars, highly magnetized neutron stars that exhibit massive periodic outbursts of energy. Another possibility suggested is core-collapse supernovae of average size stars.

What’s in the Sky?

September 26; 2am; south-southeast: A waning gibbous Moon is near the Pleiades cluster

October 1; 5:30am; east: A waning crescent Moon is near open cluster M44