Spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source.
The focusing of the radiation generated by a polarization current with a superluminally rotating distribution pattern is of a higher order in the plane of rotation than in other directions. Consequently, our previously published [J. Opt. Soc. Am. A24, 2443 (2007)] asymptotic approximation to the val...
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
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Optical Society of American (OSA)
2008
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| _version_ | 1826302241663877120 |
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| author | Ardavan, H Ardavan, A Singleton, J Fasel, J Schmidt, A |
| author_facet | Ardavan, H Ardavan, A Singleton, J Fasel, J Schmidt, A |
| author_sort | Ardavan, H |
| collection | OXFORD |
| description | The focusing of the radiation generated by a polarization current with a superluminally rotating distribution pattern is of a higher order in the plane of rotation than in other directions. Consequently, our previously published [J. Opt. Soc. Am. A24, 2443 (2007)] asymptotic approximation to the value of this field outside the equatorial plane breaks down as the line of sight approaches a direction normal to the rotation axis, i.e., is nonuniform with respect to the polar angle. Here we employ an alternative asymptotic expansion to show that, though having a rate of decay with frequency (mu) that is by a factor of order mu(2/3) slower, the equatorial radiation field has the same dependence on distance as the nonspherically decaying component of the generated field in other directions: It, too, diminishes as the inverse square root of the distance from its source. We also briefly discuss the relevance of these results to the giant pulses received from pulsars: The focused, nonspherically decaying pulses that arise from a superluminal polarization current in a highly magnetized plasma have a power-law spectrum (i.e., a flux density S infinity mu(alpha)) whose index (alpha) is given by one of the values -2/3, -2, -8/3, or -4. |
| first_indexed | 2024-03-07T05:44:34Z |
| format | Journal article |
| id | oxford-uuid:e6c445e7-d33a-455e-832b-4dc5e18e8968 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:44:34Z |
| publishDate | 2008 |
| publisher | Optical Society of American (OSA) |
| record_format | dspace |
| spelling | oxford-uuid:e6c445e7-d33a-455e-832b-4dc5e18e89682022-03-27T10:33:30ZSpectral properties of the nonspherically decaying radiation generated by a rotating superluminal source.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:e6c445e7-d33a-455e-832b-4dc5e18e8968EnglishSymplectic Elements at OxfordOptical Society of American (OSA)2008Ardavan, HArdavan, ASingleton, JFasel, JSchmidt, AThe focusing of the radiation generated by a polarization current with a superluminally rotating distribution pattern is of a higher order in the plane of rotation than in other directions. Consequently, our previously published [J. Opt. Soc. Am. A24, 2443 (2007)] asymptotic approximation to the value of this field outside the equatorial plane breaks down as the line of sight approaches a direction normal to the rotation axis, i.e., is nonuniform with respect to the polar angle. Here we employ an alternative asymptotic expansion to show that, though having a rate of decay with frequency (mu) that is by a factor of order mu(2/3) slower, the equatorial radiation field has the same dependence on distance as the nonspherically decaying component of the generated field in other directions: It, too, diminishes as the inverse square root of the distance from its source. We also briefly discuss the relevance of these results to the giant pulses received from pulsars: The focused, nonspherically decaying pulses that arise from a superluminal polarization current in a highly magnetized plasma have a power-law spectrum (i.e., a flux density S infinity mu(alpha)) whose index (alpha) is given by one of the values -2/3, -2, -8/3, or -4. |
| spellingShingle | Ardavan, H Ardavan, A Singleton, J Fasel, J Schmidt, A Spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source. |
| title | Spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source. |
| title_full | Spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source. |
| title_fullStr | Spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source. |
| title_full_unstemmed | Spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source. |
| title_short | Spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source. |
| title_sort | spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source |
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