Observações multifreqüência de quasares CSS utilizando o VLBA

Abstract

In this thesis, I discuss the results of radio polarization observations of selected Compact Steep Spectrum sources made with the Very Long Baseline Array using selected frequencies in the 18 cm, 21 cm, 13 cm and 6 cm observing bands. An analysis of the polarized emission for 3C216, C147, 3C119 and 3C43 allowed us to conclude that they show a hook-shaped structure suggesting that it may be colliding with a dense environment since both jet brightness and fractional polarization increases at the hook. The average rotation measures in the hook are about 30% higher than the values seen in superluminal knots nearest to the core component with rotation measures exceeding 1500 ± 200 rad m2. The polarized flux suggests that although the average Faraday depth < neBd > increases towards the core within the first 80 pc of the jet, it becomes higher as the jet bends. The source components which are nearest to the cores are generally unpolarized even at such short wavelength, suggesting that the spread in the λ2 polarization spectra is much narrower than in extended sources and that the wavelengths at which the fractional polarization falls by a half of the value at zero depolarization may be in the submillimeter wavelengts. The properties of the Faraday depolarization and rotatation seen in the selected objects sources are briefly discussed, as well as hypothesis to interpret them.