Pagan I: Multi-Frequency Polarimetry of Agn Jets With KVN

Abstract

Active Galactic Nuclei (AGN) with bright radio jets offer the opportunity to study the structure of and physical conditions in relativistic outflows. For such studies, multi-frequency polarimetric very long baseline interferometric (VLBI) observations are important as they directly probe particle densities, magnetic field geometries, and several other parameters. We present results from first-epoch data obtained by the Korean VLBI Network (KVN) within the frame of the P lasma Physics of Active Galactic N uclei (PAGaN) project. We observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129 GHz in dual polarization mode. Our observations constrain apparent brightness temperatures of jet components and radio cores in our sample to > 10 8.01 K and > 10 9.86 K, respectively. Degrees of linear polarization m L are relatively low overall: less than 10%. This indicates suppression of polarization by strong turbulence in the jets. We found an exceptionally high degree of polarization in a jet component of BL Lac at 43 GHz, with m L ∼ 40%. Assuming a transverse shock front propagating downstream along the jet, the shock front being almost parallel to the line of sight can explain the high degree of polarization.

Revealing the Nature of Blazar Radio Cores through Multifrequency Polarization Observations with the Korean VLBI Network

“…In early 2017, we launched a KVN large program, the Plasma-physics of Active Galactic Nuclei (PAGaN) project (see J.-Y. Kim et al 2015;Oh et al 2015 for related studies), for monitoring about 14 AGNs at the four KVN frequencies in dual polarization mode almost every month. 1 One of the main scientific goals of the project is a systematic study of RMs of blazars at mm 6).…”

Pagan Ii: The Evolution of Agn Jets on Sub-Parsec Scales

“…In the present paper (PAGaN II), we present and discuss our first results from KaVA mapping observations. In a companion paper (PAGaN I, Kim et al 2015), we present first results from polarimetric observations with KVN.…”

Observations of nearby relativistic jets with EAVN and EATING VLBI

“…3C84 is a rare object that enables us to study the evolution of the active parsec-scale jet and its interaction with the external medium because of the dense gas-rich nuclear environment. Over the past years the source has intensively been monitored by VERA and KVN (Nagai et al (2010); Suzuki et al (2012); Kim et al (2015); Hodgson et al (2018)). From 2015, we started monthly 43 GHz observations of this source with KaVA (Fig.1).…”