1. Pulsar Polarization studies at low radio frequencies
Dipanjan Mitra
Ncra, Tifr, Pune India
Collaborators: J Rankin, S Johnston, A Karasterigiou, S Kudale Y Gupta, J Gil
Thanks to GMRT / NCRA colleagues for their support during various projects
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2. Polarization observation at low frequencies (GMRT)
150 MHz
325 MHz
Mitra, Gupta, Kudale (2004)
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3. GMRT – Parkes, Pulsar Polarization survey:243, 325, 660, 1400, 3100 MHz
Johnston, Karasterigiou, Mitra, Gupta (2008)
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4. 19/02/2019

5. Average Polarization Properties
Linear polarization of pulsars decreases with increasing frequency
RFM , OPM
PA traverses often don’t agree with RVM and sometimes are frequency dependent.
Circular polarization is usually, higher towards the pulse centre
Younger pulsars are more polarized than older pulsars
All these indicate that average polarization properties results from some incoherent averaging process.
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6. Complication in Pulsar Polarization: PSR B0329+54
Mitra, Rankin, Gupta 2007
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7. The kinky features are frequency Independent, and spans a range of
90 degrees in PA
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8. Core Intensity dependent polarization behaviour
If pulsars after supernova kicks move
along the rotation axis then one can find
the X mode or O mode of emission
O mode should suffer from propagation
effects
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9. More examples of PA distortions
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10. Examples of PA distortions in single pulses
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11. 90 deg PA SWINGS
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12. Highly polarized, narrow emission pulses
With sign changing circular. Single particle
Curvature radiation like emission
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13. Core intensity dependence
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15. PA swing due to averaging Of coherent emission
A/R causing shift in the PA
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16. PA below the core emission is a result of
Incoherent addition of several smaller units of emission with OPM jumps in a given subpulse. This result maybe confirmed by the observed 90 deg PA swings, and sign changing circular, low subpulse polarization
Due to height dependent emission of the core. This result arises from the earlier
Arrival of the core emission with intensity.
The smaller units of emission are highly polarized and show sign changing
Circular , just like a single particle curvature radiation.
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17. Partial cone pulsars
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18. Flared Pulses
Mitra, Rankin, Sarala 2008
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19. 19/02/2019

20. A/R effect
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21. Episiodic illumination : There are different from flared pulses
Rankin et al 2007
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22. Conclusion
Probability of pulsar emission varies from almost 95% to ~3% across the
Pulse.
The polarization properties of partial cones are just like other normal pulsars
And the conal emission seems to arise from about km (like other
Pulsars).
Collaborators: J Rankin, S Johnston, A Karasterigiou, S Kudale Y Gupta, J Gil
Thanks to GMRT / NCRA staff for their support during various projects
19/02/2019