Interpretation of the zebra pattern in the Jovian kilometric radiation

Zlotnik, E. Ya.; Шапошников, В. Е.; Зайцев, В. В.

doi:10.1002/2016ja022655

Cited by 9 publications

(22 citation statements)

References 27 publications

(55 reference statements)

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“…Recently, Zlotnik et al (2016) proposed an alternative mechanism of zebra structure formation in Jovian kilometer radiation which was observed by Cassini at low frequencies (30-70 kHz, Kurth et al 2001). The model is based on the DPR at the ion cyclotron harmonics.…”

Section: Discussionmentioning

confidence: 99%

“…Produced by the DPR effect at the ion cyclotron harmonics, the low-frequency plasma waves cannot escape the source and should be first transformed to the highfrequency electromagnetic waves ( f em ) in a non-linear coalescence process with a high-frequency mode (e.g., with plasma waves at upper hybrid frequency). Coalescence of these waves ( f em = s f ci + f ce ) results in generation of electromagnetic waves with a spectrum in the form of ZP (see Zlotnik et al (2016) for more details).…”

Section: Discussionmentioning

confidence: 99%

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Zebra pattern in decametric radio emission of Jupiter

Panchenko

Rošker

Rücker

et al. 2018

A&A

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We report the systematic analysis of zebra-like fine spectral structures in decametric frequency range of Jovian radio emission. Observations were performed by the large ground-based radio telescope URAN-2 during three observation campaigns between, Sep., 2012, and May, 2015. In total, 51 zebra pattern (ZP) events were detected. These rare fine radio features are observed in frequency range from 12.5 to 29.7 MHz as quasi-harmonically related bands of enhanced brightness. ZPs are strongly polarized radio emission with a duration from 20 s to 290 s and flux densities ~105−106 Jy (normalized to 1 AU), that is, 1–2 orders lower than for Io-decametric radio emission (DAM). Occurrence of the events does not depend on the position of Io satellite but is strongly controlled by the Jovian central meridian longitude (CML). ZPs are mainly detected in two active sectors of Jovian CMLs: 100∘ to 160∘ for Northern sources (right-handed polarized) and 300∘ and 60∘ (via 360∘) for the Southern sources (left-handed). The frequency interval between neighboring stripes is from 0.26 to 1.5 MHz and in most cases this interval increases with frequency. We discussed the double plasma resonance with electrons or ions as a possible source of the ZPs. The performed analysis of the observations allows us to conclude that the observed ZPs are a new type of narrow band spectral structures in the Jovian DAM.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Zebra pattern in decametric radio emission of Jupiter

Panchenko

Rošker

Rücker

et al. 2018

A&A

Self Cite

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“…Recently Zlotnik et al [2016] proposed an alternative mechanism of zebra structure formation in Jovian kilometer radiation observed by Cassini at low frequencies (30-70 kHz) [Kurth et al, 2001]. The model is based on the double plasma resonance with ion cyclotron harmonics which involves the excitation of ion cyclotron waves at the lower hybrid frequency and then a non-linear transformation of this low frequency emission to high frequency waves due to a coalescence process with a high frequency mode, e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless there is a weak point in the model of the Jovian DAM zebra pattern generation at DPR with ions. According to the theory proposed by Zlotnik et al [2016] the low plasma waves cannot escape the source and should be first transformed to the high frequency waves in a non-linear coalescence process f = sf ci + f ce . Since f ce >> f ci , the resulting frequency will be f ≈ f ce and these high frequency waves can be observed as zebra stripes.…”

Section: Discussionmentioning

confidence: 99%

Zebra-like fine spectral structures in Jovian decametric radio emission

Panchenko¹,

Rošker²,

Rücker³

et al. 2018

Planetary Radio Emissions Viii

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We report the first systematic analysis of zebra-like fine spectral structures in the decametric frequency range of Jovian radio emission (DAM). These zebra patterns are observed in the frequency range from 12 to 30 MHz as a quasi-harmonically related bands (from 3 to 9) of enhanced brightness. The features have been observed by the ground-based radio telescope URAN-2 (Poltava, Ukraine). In total, 55 zebra pattern events have been detected during the period from September 2012 to March 2016. The minimum duration of one single zebra pattern was 20 s, and the maximum one was 4 min 50 s. The intensity of the zebra stripes is 1-2 magnitudes lower than the intensity of Io-controlled DAM. The numbers of stripes in one event may vary in time. The frequency interval between neighboring stripes is from 0.26 to 1.5 MHz. The zebra patterns are strongly polarized and have been observed as right-handed and left-handed polarized radio emission. The zebra patterns are mainly detected in two active sectors of Jovian CMLs: 100 • to 160 • for northern sources (righthanded polarized) and between 275 • and 60 • (via 360 • ) for the southern sources (left-handed). No correlation with the position of Io has been detected. We conclude that the observed zebra patterns are a new type of narrow band spectral structures in the Jovian decametric radio emission.

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“…According to this model the kilometer radio emission sources that can produce the zebra pattern are located in the region of the equatorial current sheet of Jupiter along the magnetic field lines, that is, across the current sheet. The model with the sources located along the current sheet, that is, across the field lines, was considered in Zlotnik et al (). In this paper it was shown that both models do not correspond to the results observed.…”

Section: Introductionmentioning

confidence: 99%

Double Plasma Resonance at Ion Cyclotron Harmonics in the Jovian Magnetosphere

2018

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The ion cyclotron waves instability near the frequencies of ionic cyclotron harmonics is studied under conditions typical for the Jovian kilometer radio emission source. This instability is caused by the presence of the ions with a nonequilibrium loss cone-type distribution function in the source. Expressions for the growth rate of the ion cyclotron wave's instability are obtained, and it is shown that the amplification of these waves significantly increases when the frequency of the lower-hybrid resonance coincides with one of the ion cyclotron harmonics. Possible mechanisms for conversion of the ion cyclotron waves excited in the Jovian kilometer radio emission source into electromagnetic radiation are discussed. It is shown that the conversion of ion cyclotron waves, due to their coalescence with high-frequency plasma waves, is possible only into ordinary electromagnetic waves, while the process capable of providing conversion of ion cyclotron waves into fast extraordinary electromagnetic waves is scattering by suprathermal electron fluxes. In the latter, despite the thermal spread of electron velocities, the radiation that leaves the source region is concentrated in a narrow frequency range Δ ≪ near the local gyrofrequency ≃ Be , and the polarization of this radiation corresponds to the extraordinary wave. The estimates of the electron energy, which is necessary for such conversion, have shown the possibility of the process realizing under conditions characteristic for the Jovian kilometer radio emission source.

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Interpretation of the zebra pattern in the Jovian kilometric radiation

Cited by 9 publications

References 27 publications

Zebra pattern in decametric radio emission of Jupiter

Zebra pattern in decametric radio emission of Jupiter

Zebra-like fine spectral structures in Jovian decametric radio emission

Double Plasma Resonance at Ion Cyclotron Harmonics in the Jovian Magnetosphere

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