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In recent studies, several AGN have exhibited gradients of the Faraday Rotation Measure (RM) transverse to their parsec-scale jet direction. Faraday rotation likely occurs as a result of a magnetized sheath wrapped around the jet. In the case of 3C 273, using Very Long Baseline Array multi-epoch observations at 5, 8 and 15 GHz in 2009--2010, we observe that the jet RM has changed significantly towards negative values compared with that previously observed. These changes could be explained by a swing of the parsec-scale jet direction which causes synchrotron emission to pass through different portions of the Faraday screen. We develop a model for the jet-sheath system in 3C 273 where the sheath is wider than the single-epoch narrow relativistic jet. We present our oversized sheath model together with a derived wide jet full intrinsic opening angle $\alpha_\mathrm{int}=2.1^\circ$ and magnetic field strength $B_{||}=3$ $\mu$G and thermal particle density $N_\mathrm{e}=125~\mathrm{cm}^{-3}$ at the wide jet--sheath boundary 230 pc downstream (deprojected) from its beginning. Most of the Faraday rotation occurs within the innermost layers of the sheath. The model brings together the jet direction swing and long-term RM evolution and may be applicable to other AGN jets that exhibit changes of their apparent jet direction., Comment: 10 pages, 9 figures. Accepted to the Astrophysical Journal

There are several methods to calculate the radiative and kinetic power of relativistic jets, but their results can differ by one or two orders of magnitude. Therefore, it is necessary to perform a calibration of the jet power, to understand the reasons for these differences (whether wrong hypotheses or intrinsic source variability), and if it is possible to converge to a reliable measurement of this physical quantity. We present preliminary results of a project aimed at calibrating the power of relativistic jets in active galactic nuclei (AGN) and X-ray binaries (XRB). We started by selecting all the AGN associations with known redshift in the Fourth Fermi LAT Gamma-Ray Catalog (4FGL). We then calculated the radiative and/or kinetic powers from available data or we extracted this information from literature. We compare the values obtained for overlapping samples and highlight early conclusions., Comment: 7 pages, 4 figures. Poster presented at High Energy Phenomena in Relativistic Outflows (HEPRO) VII, Barcelona (Spain), July 9-12, 2019. Accepted for publication on Proceedings of Science (PoS)