High-Sensitivity AGN Polarimetry at Sub-Millimeter Wavelengths

• Published in: Galaxies
• Main Authors: Ivan Martí-Vidal, Sébastien Muller
• Format: Article
• Language: English
• Published: MDPI AG 2017-10-01
• Subjects: Active galactic nuclei; Graviational lenses; Polarization; Interferometry; PKS 1830-211; B0218+359
• Online Access: https://www.mdpi.com/2075-4434/5/4/65

The innermost regions of radio loud Active Galactic Nuclei (AGN) jets are heavily affected by synchrotron self-absorption, due to the strong magnetic fields and high particle densities in these extreme zones. The only way to overcome this absorption is to observe at sub-millimeter wavelengths, although polarimetric observations at such frequencies have so far been limited by sensitivity and calibration accuracy. However, new generation instruments such as the Atacama Large mm/sub-mm Array (ALMA) overcome these limitations and are starting to deliver revolutionary results in the observational studies of AGN polarimetry. Here we present an overview of our state-of-the-art interferometric mm/sub-mm polarization observations of AGN jets with ALMA (in particular, the gravitationally-lensed sources PKS 1830−211 and B0218+359), which allow us to probe the magneto-ionic conditions at the regions closest to the central black holes.