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Abstract: We present simulations of scattering phenomena which are important in pulsarobservations, but which are analytically intractable. The simulation code,which has also been used for solar wind and atmospheric scattering problems, isavailable from the authors. These simulations reveal an unexpectedly importantrole of dispersion in combination with refraction. We demonstrate the effect ofanalyzing observations which are shorter than the refractive scale. We examinetime-of-arrival fluctuations in detail: showing their correlation withintensity and dispersion measure; providing a heuristic model from which onecan estimate their contribution to pulsar timing observations; and showing thatmuch of the effect can be corrected making use of measured intensity anddispersion. Finally, we analyze observations of the millisecond pulsarJ0437$-$4715, made with the Parkes radio telescope, that show timingfluctuations which are correlated with intensity. We demonstrate that thesetiming fluctuations can be corrected, but we find that they are much largerthan would be expected from scattering in a homogeneous turbulent plasma withisotropic density fluctuations. We do not have an explanation for these timingfluctuations.



Author: W. A. Coles, B. J. Rickett, J. J. Gao, G. Hobbs, J. P. W. Verbiest

Source: https://arxiv.org/







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