A repeating fast radio burst source in a globular cluster
  Fast radio bursts (FRBs) are exceptionally luminous flashes of unknown
physical origin, reaching us from other galaxies (Petroff et al. 2019). Most
FRBs have only ever been seen once, while others flash repeatedly, though
sporadically (Spitler et al. 2016, CHIME/FRB Collaboration et al. 2021). Many
models invoke magnetically powered neutron stars (magnetars) as the engines
producing FRB emission (Margalit & Metzger 2018, CHIME/FRB Collaboration et al.
2020). Recently, CHIME/FRB announced the discovery (Bhardwaj et al. 2021) of
the repeating FRB 20200120E, coming from the direction of the nearby grand
design spiral galaxy M81. Four potential counterparts at other observing
wavelengths were identified (Bhardwaj et al. 2021) but no definitive
association with these sources, or M81, could be made. Here we report an
extremely precise localisation of FRB 20200120E, which allows us to associate
it with a globular cluster (GC) in the M81 galactic system and to place it ~2pc
offset from the optical center of light of the GC. This confirms (Bhardwaj et
al. 2021) that FRB 20200120E is 40 times closer than any other known
extragalactic FRB. Because such GCs host old stellar populations, this
association strongly challenges FRB models that invoke young magnetars formed
in a core-collapse supernova as powering FRB emission. We propose, instead,
that FRB 20200120E is a highly magnetised neutron star formed via either
accretion-induced collapse of a white dwarf or via merger of compact stars in a
binary system (Margalit et al. 2019). Alternative scenarios involving compact
binary systems, efficiently formed inside globular clusters, could also be
responsible for the observed bursts.
