This artist’s impression represents the path of the fast radio burst FRB 181112 traveling from a distant host galaxy to reach the Earth. FRB 181112 was pinpointed by the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope. Follow-up observations with ESO’s Very Large Telescope (VLT) revealed that the radio pulses have passed through the halo of a massive galaxy on their way toward Earth. This finding allowed astronomers to analyse the radio signal for clues about the nature of the halo gas. (ESO/M. KORNMESSER)

One Cosmic Mystery Illuminates Another, As Fast Radio Burst Intercepts A Galactic Halo

There’s so much we don’t know about fast radio bursts and galactic halos. Combined, we get a unique window on the Universe.

Deep in space, mysterious signals known as Fast Radio Bursts (FRBs) stream towards Earth.

The host galaxies of fast radio bursts remain mysterious for most of the FRBs we’ve seen, but a few of them have had their host galaxy’s detected. For FRB 121102, whose repeating bursts were extremely polarized, the host was identified as a dwarf galaxy with an active galactic nucleus. Perhaps interestingly, the stars within it, on average, have far fewer heavy elements (and hence, rocky, potentially habitable planets) than the ones in our Milky Way. (GEMINI OBSERVATORY/AURA/NSF/NRC)

These FRBs last milliseconds or less, originate in ultra-distant galaxies, and sometimes repeat.

Waterfall plot of the fast radio burst FRB 110220 discovered by Dan Thornton (University of Manchester). The image shows the power as a function of time (x axis) for more than 800 radio frequency channels (y axis) and shows the characteristic sweep one expects for sources of galactic and extragalactic origin. FRBs come as either single or multiple discrete bursts lasting from tens of microseconds to a few milliseconds, but no longer. (MATTHEW BAILES / SWINBURNE UNIVERSITY OF TECHNOLOGY / THE CONVERSATION)

Although scientists have studied them intensely since their discovery, their origins remain mysterious.

The Universe is full of two trillion galaxies, each containing hundreds of billions of stars on average, with countless more to come in the future. Yet we need two galaxies to be very well aligned, serendipitously so, for a FRB originating in one to pass through the halo of another in the foreground. (NASA, ESA, J. JEE (UNIVERSITY OF CALIFORNIA, DAVIS), J. HUGHES (RUTGERS UNIVERSITY), F. MENANTEAU (RUTGERS UNIVERSITY AND UNIVERSITY OF ILLINOIS, URBANA-CHAMPAIGN), C. SIFON (LEIDEN OBSERVATORY), R. MANDELBUM (CARNEGIE MELLON UNIVERSITY), L. BARRIENTOS (UNIVERSIDAD CATOLICA DE CHILE), AND K. NG (UNIVERSITY OF CALIFORNIA, DAVIS))

Meanwhile, an estimated 2 trillion galaxies populate our observable Universe.