Physics

Interstellar medium

Millisecond

Galaxy

Optics

Astronomy

Radio telescope

Scattering

Fast radio burst

Astrophysics

Quantum mechanics

Milky Way

Radio spectrum

Radio wave

Nature

Fast radio bursts (FRBs) are highly dispersed millisecond-duration radio flashes probably arriving from far outside the Milky Way1,2. This phenomenon was discovered at radio frequencies near 1.4&nbsp;gigahertz and so far has been observed in one case3 at as high as 8&nbsp;gigahertz, but not at below 700&nbsp;megahertz in spite of substantial searches at low frequencies4–7. Here we report detections of 13 FRBs at radio frequencies as low as 400&nbsp;megahertz, on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) using the CHIME/FRB instrument8. They were detected during a telescope pre-commissioning phase, when the sensitivity and field of view were not yet at design specifications. Emission in multiple events is seen down to 400&nbsp;megahertz, the lowest radio frequency to which the telescope is sensitive. The FRBs show various temporal scattering behaviours, with the majority detectably 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, as described in a companion paper9. The overall scattering properties of our sample suggest that FRBs as a class are preferentially located in environments that scatter radio waves more strongly than in the diffuse interstellar medium in the Milky Way. Thirteen fast radio bursts—astrophysical events that last on the order of a millisecond—have been discovered at frequencies as low as 400&nbsp;megahertz, including only the second known repeating burst.

Observations of fast radio bursts at frequencies down to 400 megahertz