The source of a mysterious radio wave burst, picked up only once, has been discovered; a galaxy more than three-and-a-half billion light-years away.
Naturally-occurring radio waves are not a new thing. Thanks to being made up of electromagnetic energy, they can be emitted by things like lightning and can travel at the speed of light. Radio broadcasts from decades ago can still be received if you go far out enough in space. Space also sends out its own radio waves, and now, we know exactly where they are coming from.
Last month, astronomers working with the Australian Square Kilometre Array announced that they had pinpointed the origin of a single Fast Radio Burst to a galaxy roughly 3.6 billion light-years away. It marks the second time that the source of such a burst has been pinpointed, with the first one in 2017 coming from a small galaxy three billion light-years away. The difference is that while the signal captured then is still being regularly recorded, the second was a once-off phenomenon.
A Fast Radio Burst, or FRB, is a pulse of energy that emanates from an unknown source in space. They are broadband, meaning that they occur across a wide range of radio frequencies, and maintain the same level of energy throughout the time that they are recorded.
FRB 180924, as the latest burst is referred to, was first captured by the Array in Australia and then backed up by observations from telescopes in Hawaii and Chile. This helped to determine its exact origin, a large galaxy similar in size to the Milky Way and primarily occupied by old stars.
Planet Earth has been aware of these FRBs for some time now. Back in 2007, researchers at the Parkes radio telescope discovered data from 2001 that showed a burst of radio waves that seemed to come from a satellite dwarf galaxy in the Milky Way (lasting only five milliseconds). After that, more data began to appear that showed that these bursts did not happen rarely but were regular occurrences throughout space.
One of the details noted by the astronomers who pinpointed the source of FRB 180924 was how the galaxy it came from posed no unique or special features. This is noteworthy as the source of the burst must be using large amounts of energy to charge them. Scientists reckon that the amount of electromagnetic energy used is equivalent to the amount of energy released by our sun over a period of 80 years.