Zooming in on the origins of fast radio bursts

The Australian SKA Pathfinder (ASKAP) telescope made headlines in 2019 as the first instrument to localise a non-repeating fast radio burst (FRB). Since then, it has localised several more nonrepeating bursts, and now Dr Shivani Bhandari of CSIRO has used multi-wavelength follow-up to examine their host galaxies.

The origin of FRBs remains one of the most intriguing mysteries of modern astronomy but this first detailed study of host galaxies rules out some of the more extreme theories previously put forward. Dr Bhandari and her team identified the exact location of four FRBs.

“These precisely localised FRBs came from the outskirts of their home galaxies, removing the possibility that they have anything to do with supermassive black holes,” Dr Bhandari said.

They found all four bursts came from massive galaxies that are forming new stars at a modest rate, very similar to the Milky Way.

The first FRB ever localised was one that bursts repeatedly. That source, FRB121102, is coincident with a dwarf galaxy. However, follow-up of a second repeater, and the non-repeating ASKAP bursts, shows that FRB121102 is not typical.

These latest findings lend weight to the idea that FRBs might originate from compact objects.

“Models such as mergers of compact objects like white dwarfs or neutron stars, or flares from magnetars created by such mergers, are still looking good,” said CSIRO Prof. Elaine Sadler, a co-author on the paper, which was published in the Astrophysical Journal Letters.

Dame Jocelyn Bell Burnell, who first discovered pulsars, praised the research. “Positioning the sources of FRBs is a huge technical achievement, and moves the field on enormously,” Dame Jocelyn said. “We may not yet be clear exactly what is going on, but now, at last, options are being ruled out.”

Dame Jocelyn Bell Burnell and CSIRO astronomer Dr Shivani Bhandari, during Dame Jocelyn’s visit to Sydney in 2019

Shivani Bhandari

The ASKAP telescope is located at CSIRO’s Murchison Radio-astronomy Observatory (MRO) in Western Australia. CSIRO acknowledges the Wajarri Yamatji as the traditional owners of the MRO site.

Cover: CSIRO’s ASKAP radio telescope in Western Australia detected the precise location of four fast radio bursts. Follow-up observations by NRAO’s JVLA and CSIRO’s ATCA radio telescopes and the world’s largest optical telescopes – Gemini South, ESO’s Very Large Telescope, Magellan Baade, Keck and LCOGT-1m – identified and imaged the host galaxies. Credit: CSIRO/Sam Moorfield

By Annabelle Young (CSIRO)