Study of the polarized decametric radio emission measured by riometers

Abstract

This proposal focuses on the identification and characterization of different radio sources (38.2 MHz) detected, in 2012, by riometers located at Space Physics and Astronomy Observatory of University of Vale do Paraíba (UNIVAP), in São José dos Campos, SP. Riometers are passive ground-based antennas continuously receiving electromagnetic radiation from space, in a frequency range of 20 - 200 MHz, called Cosmic Noise. Variations of the Cosmic Noise flux measured near ground usually means electronic density changes in the low-ionosphere. Thus, riometers are used as an aeronomy instrument. However, the radio flux received by riometers can vary due to the intensification of other radio sources in the sky. In the Solar System, there are two important radio sources at the same frequency as Cosmic Noise: The Sun (during some Coronal Mass Ejection and/or Solar Flares events) and Jupiter (during the interaction of some solar transient structures or its moon Io with its strong magnetic field). While the cosmic noise flux arrives without a preferential polarization, the decametric flux from those other sources presents a strong circular polarization degree. The goal of this study is distinguish, using the information carried by the polarization of the detected radiation, the different sources of the radio emission detected by UNIVAP's riometer, characterizing it through the periodic component analysis and the comparison with other datasets, which will allow us to evaluate the viability of the use of this instrument (riometer) in other types of astrophysical studies.