The host galaxies and progenitors of Fast Radio Bursts localized with the Australian Square Kilometre Array Pathfinder

TL;DR

ASKAP's precise localization of FRBs has revealed their host galaxies are typically massive, with properties suggesting progenitors other than active galactic nuclei or young magnetars from superluminous supernovae.

Contribution

This study provides the first detailed analysis of host galaxies for multiple localized FRBs, challenging some existing progenitor models and supporting a broader range of possibilities.

Findings

FRBs are hosted in massive galaxies with modest star formation.

Localized FRBs are often found in galaxy outskirts, ruling out some progenitor models.

Host galaxy properties disfavor young magnetar origins from SLSNe.

Abstract

The Australian SKA Pathfinder (ASKAP) telescope has started to localize Fast Radio Bursts (FRBs) to arcsecond accuracy from the detection of a single pulse, allowing their host galaxies to be reliably identified. We discuss the global properties of the host galaxies of the first four FRBs localized by ASKAP, which lie in the redshift range $0.11<z<0.48$. All four are massive galaxies (log( $M_{*}/ M_{\odot}$) $\sim 9.4 -10.4$) with modest star-formation rates of up to $2M_{\odot}$yr$^{-1}$ -- very different to the host galaxy of the first repeating FRB 121102, which is a dwarf galaxy with a high specific star-formation rate. The FRBs localized by ASKAP typically lie in the outskirts of their host galaxies, which appears to rule out FRB progenitor models that invoke active galactic nuclei (AGN) or free-floating cosmic strings. The stellar population seen in these host galaxies also disfavors models in which all FRBs arise from young magnetars produced by superluminous supernovae (SLSNe), as proposed for the progenitor of FRB 121102. A range of other progenitor models (including compact-object mergers and magnetars arising from normal core-collapse supernovae) remain plausible.