Astronomers detect another batch of mysterious repeating fast radio bursts

Brittany A. Roston - Jan 9, 2019, 2:13 pm CST
Astronomers detect another batch of mysterious repeating fast radio bursts

In 2007, an astronomy professor and his student detected a fast radio burst, a phenomenon that has been detected many times in the years since. The mystery deepened in 2015 when multiple bursts were discovered to have come from the same location, the origins of which are still unknown. A newly published study reveals that scientists have detected a second source of these repeat fast radio bursts, as well as multiple FRBs from different locations.

A fast radio burst lasts only a few milliseconds; due to both the very brief appearance and the inability to predict where they will happen, it has proven very difficult for astronomers to study the FRBs. A lucky moment in 2015 resulted in the detection of multiple FRBs coming from the same location, which differs from random fast radio bursts that appear isolated in different locations.

There’s no definitive cause of these fast radio bursts and it’s unclear what caused multiple FRBs from the same location. However, a new facility in Canada called CHIME has added a new piece to the puzzle by detecting a second source of repeat fast radio bursts, as well as multiple instances of single FRBs.

CHIME, which is short for Canadian Hydrogen Intensity Mapping Experiment, is a type of interferometric radio telescope featuring half-cylinder dishes that observe the same section of sky every day. As the Earth rotates, the portion of the universe in that small sky section is visible to the telescope, which was designed specifically to monitor FRBs.

Late last year, while the system was still being calibrated, CHIME managed to observe multiple FRBs during a brief period of time when it was on. A total of 13 fast radio bursts were observed, but six of them were of particular interest: they all came from the same location.

The researchers explain in their new study:

The FRBs show various temporal scattering behaviours, with the majority significantly scattered, and some apparently unscattered to within measurement uncertainty even at our lowest frequencies. Of the 13 reported here, one event has the lowest dispersion measure yet reported, implying that it is among the closest yet known, and another has shown multiple repeat bursts…

The presence of a second source of repeat FRBs — as well as the detection during CHIME’s brief active pre-commission period — hints at the potential existence of two different types of radio bursts, one that happen only once and another that results in multiple bursts from one spot. A second paper published on the discovery details the repeating fast radio bursts, explaining:

This second repeater, found among the first few CHIME/FRB discoveries, suggests that there exists — and that CHIME/FRB and other wide-field, sensitive radio telescopes will find — a substantial population of repeating FRBs.

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