AGNs

One of the main contributors to the radio sky are the relativistically-beamed emission of the parsec-scale relativistic jets ejected from the nuclear regions of the Active Galactic Nuclei (AGN). The AGN contains a supermassive Black Hole (SMBH) at its center; the relativistic jets are formed, collimated and accelerated close to the SMBH, with the accretion disk and the magnetic fields playing a relevant role in their generation and collimation. The detailed structure of these relativistic jets can be probed in exquisite detail thanks to the VLBI technique, getting closer to the SMBH as we move towards millimeter wavelengths. Depending on the distance to the AGNs and the Black Hole mass, the VLBI observations probe regions of tens (for SgrA*, M81, M87) to thousands of Schwarzschild Radii around the SMBH.

Polarimetric Observations of the inner regions with the GMVA

The Global Millimeter VLBI Array (GMVA; http://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/) provides high quality high angular resolution (~40 microarcsec) images of emission regions in AGN jets which are self-absorbed at lower frequencies. GMVA 86-GHz polarimetric images reveal the relativistic jet magnetic field properties (across and along the jet) and their structural changes in those regions where the jets are supposed to be launched and collimated. One of our external collaborators, Iván Martí-Vidal, has developed a semi-automatic pipeline for the calibration of the 86 GHz full polarization calibration (Martí-Vidal et al. 2012, A&A 542, A197), permitting a systematic high angular resolution, high dynamic range analysis of the polarized structure of the most compact sources at 86 GHz. Within the previous research project, we have been granted with GMVA observing time of compact sources which have a high average degree of polarization at mm-wavelengths, flat spectral index and strong variability in order to image the polarized fine structure of their central regions at sub-parsec scales and its time evolution. We have already got data for two sources, 4C 39.25 and 1055+018, both of them with high degree of polarization, and bursting at the time of the observations. The detailed analysis is ongoing. we perfo0rmed simultaneous observations at 7mm, whose preliminary images are shown.