DOI

https://doi.org/10.48717/hpc8-9d96

Project

GP061

Title

The true nature of the jet base in 3C84

Abstract

The radio galaxy 3C84 displays a unique blend of brightness, large black hole mass and proximity. Recently, a new jet component appeared in the northern core region. This region is oriented perpendicular to the outer jet and is hypothesized to correspond to the physical jet base. Here we propose a high spatial resolution spectral-index study of the northern jet on sub-mas scales, taking advantage of the power of global VLBI at 22/43 GHz. The quasi- simultaneous imaging will overcome limitations by source variability. We primarily address the spectral index and polarization of the northern core region. From measurements of the transverse spectral index gradient in E-W direction we can discriminate between competing physical interpretation, such as a standing shock or a Blandford-Payne jet apex. The high dynamic range imaging will also facilitate a more accurate imaging of the inner double rail and the jet expansion profile. Polarization imaging at two frequencies will enable us to determine the B-field geometry and rotation measure of the jet origin on scales down to 1000 Schwarzschild radii. This is a resubmission of proposal G20C001, whose observations were unsuccessful due to significant sensitivity loss at the VLBA.