Kavli Affiliate: Kiyoshi W. Masui
| First 5 Authors: Ryan Mckinven, Mohit Bhardwaj, Tarraneh Eftekhari, Charles D. Kilpatrick, Aida Kirichenko
| Summary:
Fast radio bursts (FRBs) last for milliseconds and arrive at Earth from
cosmological distances. While their origin(s) and emission mechanism(s) are
presently unknown, their signals bear similarities with the much less luminous
radio emission generated by pulsars within our Galaxy and several lines of
evidence point toward neutron star origins. For pulsars, the linear
polarisation position angle (PA) often exhibits evolution over the pulse phase
that is interpreted within a geometric framework known as the rotating vector
model (RVM). Here, we report on a fast radio burst, FRB 20221022A, detected by
the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and localized to a
nearby host galaxy ($sim 65; rm{Mpc}$), MCG+14-02-011. This one-off FRB
displays a $sim 130$ degree rotation of its PA over its $sim 2.5; rm{ms}$
burst duration, closely resembling the "S"-shaped PA evolution commonly seen
from pulsars and some radio magnetars. The PA evolution disfavours emission
models involving shocks far from the source and instead suggests magnetospheric
origins for this source which places the emission region close to the FRB
central engine, echoing similar conclusions drawn from tempo-polarimetric
studies of some repeating sources. This FRB’s PA evolution is remarkably
well-described by the RVM and, although we cannot determine the inclination and
magnetic obliquity due to the unknown period/duty cycle of the source, we can
dismiss extremely short-period pulsars (e.g., recycled millisecond pulsars) as
potential progenitors. RVM-fitting appears to favour a source occupying a
unique position in the period/duty cycle phase space that implies tight opening
angles for the beamed emission, significantly reducing burst energy
requirements of the source.
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