VLT/X-Shooter spectrum of the host galaxy of the ASKAP-detected FRB 20230708A, showing prominent Hα, Hβ, [O III], and [O II] emission. Best model fits for the gas emission (orange) and stellar continuum (red) are shown, with the spectral error in blue. (From Muller et al. 2025)

Despite almost 1000 published FRB detections to date, including ∼100 with confident host associations, FRB progenitors and their emission mechanisms are still not well understood. Muller et al. present Very Large Telescope (VLT)/X-Shooter spectroscopy for the host galaxies of 12 fast radio bursts (FRBs) detected by ASKAP as part of a study to better understand the objects producing FRBs. They focus on the faint host of FRB 20230708A, identified at low redshift, z=0.105. This indicates an intrinsically very low-luminosity galaxy, making it the lowest-luminosity non-repeating FRB host to date by a factor of ∼3, and slightly dimmer than the lowest-luminosity host for repeating FRBs. Its discovery demonstrates that FRBs can arise in among the faintest, metal-poor galaxies of the universe. In turn, this suggests that at least one FRB progenitor channel must include stars (or their remnants) created in very low metallicity environments. This indicates better prospects for detecting FRBs from the high-z universe where young, low-mass galaxies proliferate. The image above shows the VLT/X-Shooter spectrum of the FRB 20230708A host galaxy showing prominent Hα, Hβ, [O III], and [O II] emission, which allowed the redshift for the galaxy to be degtermined. There is a notable lack of clear [N II] emission features. The best model fits for the gas emission (orange) and stellar continuum (red) are shown, with the spectral error shown in blue.