Abstract <p>As part of the Early Science Program of the RadioAstron project, the millisecond pulsar B1937+21 was observed in October 2012. The total duration of the experiment supported by eight ground-based radio telescopes was about three hours. The radiation in both circular polarizations in the frequency band of 1644‒1676 MHz was recorded. Characteristic time and frequency scales of scintillation caused by the scattering on the interstellar plasma density fluctuations have been measured: <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1715_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="135" /> </InlineMediaObject> <EquationSource Format="TEX">\(\Delta {{t}_{{{\text{dif}}}}} = 275.2 \pm 0.1\)</EquationSource>  </InlineEquation> s and <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1715_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="120" /> </InlineMediaObject> <EquationSource Format="TEX">\(\Delta {{\nu }_{{{\text{dif}}}}} = 580 \pm 30\)</EquationSource>  </InlineEquation> kHz. The angular diameter of the scattering disk, <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1715_Article_IEq3.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="119" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\theta }_{{\text{H}}}} = 0.32 \pm 0.03\)</EquationSource>  </InlineEquation> mas, has been estimated from the decrease in the amplitude of the interferometric response at the ground–space baselines. The dependence of the visibility amplitude on the delay shows two scattering time scales: <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1715_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="108" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\tau }_{{{\text{sc}}1}}} = 110 \pm 30\)</EquationSource>  </InlineEquation> ns and <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1715_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="116" /> </InlineMediaObject> <EquationSource Format="TEX">\({{\tau }_{{{\text{sc}}2}}} = 750 \pm 100\)</EquationSource>  </InlineEquation> ns, which indicates an ellipse-like scattering disc with an axis ratio of 2.6 : 1. The drift of the visibility maximum on the residual interference frequency that was observed at the intercontinental baselines can be explained by atmospheric effects, while the dominant contribution being the additional phase shift in the troposphere above European stations.</p>

Measurement of Radio Emission Scattering Parameters at the Frequency of 1650 MHz in the Direction of Pulsar B1937+21 with Ground–Space Interferometer RadioAstron

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2025年9月1日

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E. N. Fadeev,
M. S. Burgin,
M. V. Popov,
A. G. Rudnitskiy,
T. V. Smirnova,
V. A. Soglasnov

摘要

Abstract

As part of the Early Science Program of the RadioAstron project, the millisecond pulsar B1937+21 was observed in October 2012. The total duration of the experiment supported by eight ground-based radio telescopes was about three hours. The radiation in both circular polarizations in the frequency band of 1644‒1676 MHz was recorded. Characteristic time and frequency scales of scintillation caused by the scattering on the interstellar plasma density fluctuations have been measured: \(\Delta {{t}_{{{\text{dif}}}}} = 275.2 \pm 0.1\) s and \(\Delta {{\nu }_{{{\text{dif}}}}} = 580 \pm 30\) kHz. The angular diameter of the scattering disk, \({{\theta }_{{\text{H}}}} = 0.32 \pm 0.03\) mas, has been estimated from the decrease in the amplitude of the interferometric response at the ground–space baselines. The dependence of the visibility amplitude on the delay shows two scattering time scales: \({{\tau }_{{{\text{sc}}1}}} = 110 \pm 30\) ns and \({{\tau }_{{{\text{sc}}2}}} = 750 \pm 100\) ns, which indicates an ellipse-like scattering disc with an axis ratio of 2.6 : 1. The drift of the visibility maximum on the residual interference frequency that was observed at the intercontinental baselines can be explained by atmospheric effects, while the dominant contribution being the additional phase shift in the troposphere above European stations.