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 2 M _ { \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 .