A T N F    D a i l y    A s t r o n o m y    P i c t u r e

6th of December 2023
ATNF Colloquium
Examining the validity of the Rotating Vector Model in Pulsars
Dipanjan Mitra (NCRA, TIFR)
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.

<<   |   archive   |   about   |   today   *   ATNF   |   Parkes   |   ATCA   |   Mopra   |   VLBI   |   ASKAP   |   >>