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Technical Report CMS-TR-20160209

Title Core and Conal Component Analysis of Pulsar B1933+16 – Investigation of the Segregated Modes
Author/s Dipanjan Mitra
Physics Department, University of Vermont, Burlington, VT 05405, USA
National Centre for Radio Astrophysics, Pune 411 007, India
Janusz Gil Institute of Astronomy, University of Zielona Góra, Lubuska 2, 65-265 Zielona Góra, Poland

Joanna Rankin
Department of Physics, University of Vermont, Burlington, VT 05405 USA
Sterrenkundig Instituut ‘Anton Pannekoek’, University of Amsterdam, NL-1090 GE

Mihir Arjunwadkar
Centre for Modeling and Simulation, Savitribai Phule Pune University, Pune 411 007, India
Abstract Radio pulsar B1933+16 is brightest core-radiation dominated pulsar in the Arecibo sky, and here we carry out a comprehensive high resolution polarimetric study of its radiation at both 1.5 and 4.6 GHz. At 1.5 GHz, the polarization is largely compatible with a rotating-vector model with α and β values of 125 and −1.2°, such that the core and conal regions can be identified with the primary and secondary polarization modes and plausibly with the extraordinary and ordinary propagation modes. The pulsar's single pulses are quite steady in intensity, and the fluctuation spectra analysis did not show any evidence of organized conal subpulse motion. Polarization modal segregation of profiles shows that the core is comprised of two parts, later X-mode and earlier O-mode emission. Analysis of the broad microstructures under the core showed that they have similar timescales to those of the largely conal radiation of other pulsars studied earlier. Aberration/retardation analysis was here possible for both the conal and core radiation clearly and showed physical emission heights of about 200 km for both. Further, the similar conal linear polarization orientations over the broad band between 0.77 and 4.6 GHz show very little or no change, implying that the waves emerge from the magnetosphere without suffering any rotation of the polarization vector in the magnetosphere. Comparison with other core-cone pulsars suggests that the core and conal emission arises from similar emission heights. Assuming the inner vacuum gap model we note that at these emission altitudes the frequency of the observed radiation νobs is less than the plasma frequency νp and the cyclotron frequency νB. We conclude that the radio emission properties are consistent with the theory of coherent curvature radiation by charged solitons where the condition νobs < νp < νB is satisfied. However, the differences that exist between core and conal emission in their geometric locations within a pulse, polarization and modulation properties are yet to be understood.
Keywords Magnetohydrodynamics (MHD); plasmas; pulsars: general; radiation mechanism: non-thermal; pulsar B1933+16; polarization.
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Citing This Document Dipanjan Mitra, Joanna Rankin, and Mihir Arjunwadkar , Core and Conal Component Analysis of Pulsar B1933+16 – Investigation of the Segregated Modes . Technical Report CMS-TR-20160209 of the Centre for Modeling and Simulation, Savitribai Phule Pune University, Pune 411007, India (2016); available at http://cms.unipune.ernet.in/reports/.
Notes, Published Reference, Etc. Published as Monthly Notices of the Royal Astronomical Society, 460(3) 3063-3075 (2016)
Contact dmitra AT ncra.tifr.res.in, Joanna.Rankin AT uvm.edu, mihir AT cms.unipune.ernet.in
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