Hercules A

Hercules A
Radio-Optical View of the Galaxy Hercules A - Many thanks to: NASA, ESA, S. Baum and C. O'Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA)

Monday, February 11, 2013

Modulation structures in the dynamic spectra of Jovian radio emission obtained with high time-frequency resolution

I refer to Litvinenko Lecacheux Rucker Konovalenko Ryabov Taubenschuss Vinogradov Shaposhnikov 2009:
Free pdf available.

I quote some portions of much interest to me:

"Aims: The wide-band dynamic spectra of Jovian decameter emission obtained over the last decade with high-frequency and high time resolution equipment on the largest decameter band antenna array, the Ukrainian T-shape Radio telescope (UTR-2), are presented.
Methods: We analyzed the data obtained with the Digital SpectroPolarimiter (DSP) and WaveForm Reciever (WFR) installed at UTR-2. The combination of the large antenna and high performance equipment gives the best sensitivity and widest band of analysis, dynamic range, time and frequency resolutions. The wavelet transform method and the Fourier technique was used for further data processing.
Results: The main characteristics of already known and newly detected modulation events were investigated and specified. The new receiving-recording facilities, methodology and program of observations are described in detail."

Why do we study Jovian radiation ? :

"Currently, despite continuing interest in the investigation of this phenomenon with ground-based methods (see, for instance, Nigl et al. 2007; Hess et al. 2007b; Taubenschuss et al. 2006) as well as by space missions (see, for instance Hospodarsky et al. 2004; Spilker et al. 2007; Mutel et al. 2007) there is no complete theory able to explain the origin of the radiation and the particularities appearing in the dynamic spectra of DAM (decameter) emission(Hess et al. 2007a; Zarka et al. 2007;Shaposhnikov et al. 2008)."

"...more investigations using the newer, more sensitive instruments are also very important. Discovering more weak events and the less contrasting fine time-frequency structures may provide new information about the nature and physical mechanism of the Jovian radio emission in general."

"One of the most interesting particularities of S-bursts is their rapid drift in the frequency time plane, which has no reliable explanation (see Ryabov & Gerasimova 1990, and reference therein)."

"Genova et al. (1981) found a new class of modulations, called “high frequency lanes”, which appear in the high frequency part of the dynamic spectrum. Moreover, these authors, based on the analysis of much experimental data, suggested that modulation events are either produced by the Earth’s ionosphere or by the oscillations in interplanetary medium."

Faraday modulations and Io plasma torus:

"...Therefore the observations of Faraday fringes can be used to remotely sense the electron content of the medium traversed by the wave. Moreover, this effect gives us the possibility of monitoring the latitudinal inhomogeneity of the Io plasma torus (Shaposhnikov et al. 1999)...is not yet clear what the percentage ratio is of each medium’s (Io’s plasma torus and the Earth’s ionosphere) contribution to the full Faraday rotation"

I enclose a copy of Fig. 6 showing "high frequency lanes", and Fig. 12 showing Z-envelope and superfine structure of Short bursts.

Dr. Eng. Victor Herrero-Arrieta Ph.D. M.S. Ing.Ind.