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Abstract:
More than Fifty years have passed since the discovery of pulsars, yet
the physical mechanism of their coherent radio emission is unclear.
The linear polarization position angle (PPA) tracks observed in normal
pulsars (periods > 0.1 sec) can be explained by the rotating vector
model (RVM), which forms the basis for understanding pulsar coherent
radio emission physics. In several pulsars only one RVM like PPA track
is seen while in other pulsars two parallel orthogonal tracks are
seen, and this variation can be understood as radiation coming out
from the pulsar magnetosphere to mainly consist of extraordinary or
ordinary waves polarized perpendicular or parallel to the planes of
pulsar dipolar magnetic field. However there also exists an equally
large sample of pulsars where the PPA traverses shows a complex non-RVM
pattern. This diverse behaviour is in conflict with applying a unique
emission mechanism to the pulsar population, and hence the fundamental
question of whether the outgoing waves are excited by maser or
curvature radiation (also known as antenna mechanism) had remained
unresolved. In this talk I will argue
that high quality single pulse polarimetric observations can be used
to distinguish the emission mechanism. I will showcase examples of
how highly linearly polarized signals can unravel the underlying RVM,
particularly in pulsars with PPAs showing complex patterns. This
feature strongly favours the coherent curvature radiation mechanism to
be universally applicable in the normal pulsar population.
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