A New Type of Jovian Hectometric Radiation Powered by Monoenergetic Electron Beams

B. Collet; L. Lamy; C. K. Louis; P. Zarka; R. Prange; P. Louarn; W. S. Kurth; F. Allegrini

doi:10.1029/2024JA032422

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A New Type of Jovian Hectometric Radiation Powered by Monoenergetic Electron Beams

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A New Type of Jovian Hectometric Radiation Powered by Monoenergetic Electron Beams

B. Collet, L. Lamy, C. K. Louis, P. Zarka, R. Prange, P. Louarn, W. S. Kurth and F. Allegrini

Journal of geophysical research. Space physics, Vol.129(5), e2024JA032422

05/01/2024

DOI: 10.1029/2024JA032422

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Abstract

In this study, we statistically analyze the Jovian auroral radio sources detected in situ by Juno/Waves at frequencies f below the electron cyclotron frequencyf(ce ). We first conduct a survey of Juno/Waves data over 1-40 MHz from 2016 to 2022. The 15 detected HectOMetric (HOM) sources all lie within 1-5 MHz and are both less frequent than the radio sources commonly observed slightly above f(ce )and clustered in the southern hemisphere, within similar to 90-270 degrees longitudes. We analyze these emission regions with a growth rate analysis in the framework of the Cyclotron Maser Instability (CMI), which we apply to JADE-E high cadence electron measurements. We show that the f <f(ce) emissions correspond to crossed radio sources, similar to 300 km wide. They are located in a hot and highly depleted auroral plasma environment, along flux tubes colocated with upward field-aligned current and at the equatorward edge of the main auroral oval. The wave amplification is consistent with the CMI and its free energy source consists of a shell-type electron distribution function (EDF) with characteristic energies of 0.2-5keV. More energetic, 5-50 keV, shell-type EDFs were systematically observed at higher latitudes but without any radio counterpart. Various parameters for the f < f(ce)HOM sources, reminiscent of the ones at Earth/Saturn, are compared. Other CMI-unstable EDFs, primarily loss cone ones, are systematically observed during the same intervals, giving rise to emission observed at f(ce) < f < f(ce) + 0.5%. Our analysis thus reveals that different portions of the same EDF can be CMI-unstable and simultaneously amplify radio waves below and abovef(ce).

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Details

Title: Subtitle: A New Type of Jovian Hectometric Radiation Powered by Monoenergetic Electron Beams
Creators: B. Collet - Aix-Marseille University
L. Lamy - Laboratoire d’études spatiales et d’instrumentation en astrophysique
C. K. Louis - Observatoire de Paris
P. Zarka - Laboratoire d’études spatiales et d’instrumentation en astrophysique
R. Prange - Observatoire de Paris
P. Louarn - Université Toulouse III - Paul Sabatier
W. S. Kurth - University of Iowa
F. Allegrini - Southwest Research Institute
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.129(5), e2024JA032422
Publisher: Amer Geophysical Union
DOI: 10.1029/2024JA032422
ISSN: 2169-9380
eISSN: 2169-9402
Number of pages: 24
Grant note: CNES; Centre National D'etudes Spatiales CNES and CNRS/INSU CNRS/INSU national programs of planetology (PNP) - (CEA)
Language: English
Date published: 05/01/2024
Academic Unit: Physics and Astronomy
Record Identifier: 9984627280302771

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