Close, But No FRB

There was a report about a month ago that a Fast Radio Burst (FRB) produced a repeating signal.  This is big news because we really don’t know what causes FRBs, and once they have ended it can be difficult to trace their source.  But a repeating signal means we can pinpoint their origin and potentially figure out their root cause.  It’s no wonder the astronomical community was excited…and skeptical.

The Very Large Array – literally. Credit: NRAO

Most of the FRBs that have been discovered were in archival data – data from past surveys that were given a closer look.  Only a few have been seen in real-time, so when there was a radio afterglow, astronomers were excited to trace the source to a point in the direction of a galaxy 6 Billion light years distant.

After the news broke, astronomers using the incredible sensitivity of the Jansky Very Large Array (VLA) focused in on the host galaxy to observe it, with the goal of seeing the supposed afterglow.  What they saw was a repeating source of radio waves, but one that randomly changed its intensity, sometimes dimming and other times brightening.  This is unexpected for the afterglow of an incredibly energetic event.

The source of the afterglow turned out to be the flickering of an active galactic nucleus, the bright jets of a supermassive black hole in the core of the galaxy, produced as the black hole rapidly sucks up the surrounding material.  This means that it isn’t related to the original FRB, they just happened to be in the same direction in the sky, as viewed from Earth.

This isn’t a bad outcome for the team who discovered the original FRB.  It was still one of the few that has been observed in real time, and it means that whatever is causing them isn’t a source of continuous radio waves.  The down side is that we still know very little about them, including whether they originate within our galaxy or far beyond.

Either way, science is a process, and a rigorous one at that.  Sometimes progress happens slowly, but it’s that slow progress that leads to great achievement.  I see no reason why we won’t figure out the origin of FRBs some day, as long as they keep occurring, and we keep searching.

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