On the subpulse modulation, polarization and sub-beam carousel configuration of pulsar B1857−26 |
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Authors: | Dipanjan Mitra Joanna M. Rankin |
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Affiliation: | National Centre for Radio Astrophysics, Ganeshkhind, Pune 411 007, India;Department of Physics, University of Vermont, Burlington VT 05405, USA |
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Abstract: | New Giant Metre-Wave Radio Telescope (GMRT) observations of the five-component pulsar B1857−26 provide detailed insight into its pulse-sequence modulation phenomena for the first time. The outer conal components exhibit a 7.4-rotation period, longitude-stationary modulation. Several lines of evidence indicate a carousel circulation time of about 147 stellar rotations, characteristic of a pattern with 20 beamlets. The pulsar nulls some 20 per cent of the time, usually for only a single pulse, and these nulls show no discernible order or periodicity. Finally, the pulsar's polarization-angle traverse raises interesting issues: if most of its emission comprises a single polarization mode, the full traverse exceeds 180°; or if both polarization modes are present, then the leading and the trailing halves of the profiles exhibit two different modes. In either case, the rotating-vector model fails to fit the polarization-angle traverse of the core component. |
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Keywords: | MHD plasmas polarization radiation mechanisms: non-thermal methods: data analysis pulsars: individual: B1857−26 |
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