Anomalous frequency dependence of scattering of the radio emission from the Crab pulsar |
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| Authors: | A D Kuz’min Ya N Istomin B Ya Losovskiȝ S V Logvinenko D V Dumskiȝ |
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| Institution: | 1.Lebedev Physical Institute,Russian Academy of Sciences,Moscow,Russia |
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| Abstract: | The frequency dependence of scattering of the radio emission from the Crab pulsar at the low frequencies 111, 63, and 44 MHz
has been measured and analyzed during sporadic enhancements of scattering and dispersion measure in October–December 2006
and December 2008. The frequency dependence of the scattering differs from the generally accepted dependence, τ
sc
(ν) ∝ ν
γ
, where γ = −4.0 for Gaussian and γ = −4.4 for power-law Kolmogorov distributions of inhomogeneities of the scattering medium. In intervals of enhancement, the
exponent of the frequency dependence γ decreased to −3.2(0.2) at the above frequencies. A model is proposed in which this is due to the presence of a dense plasma
structure in the nebula in the line of sight toward the pulsar, in which scattering of the radio emission on turbulence differs
from scattering in the interstellar medium. It is shown that the frequency dependence of scattering of the radio emission
can be weaker in a dense plasma than in the rarefied interstellar medium. |
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| Keywords: | |
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