DOI

https://doi.org/10.48717/p989-0y19

Project

GK053

Title

GK053 Ultra-Deep Polarization Imaging of M87. Kim et al.

Abstract

Owing to its proximity and large BH mass, the radio-galaxy M87 has been previously observed by mm-VLBI in order to study mass accretion, jet formation, and magnetic fields near the SMBH, but often with limited sensitivity. Here we propose to revisit the source with global VLBI at 7mm -- again after the last observations in 2018 which only partially succeeded. Global observations at this wavelength have the unique advantages over VLBI at shorter/longer wavelength due to brighter total and polarized intensity and an exceedingly higher imaging sensitivity (10 times better than at 3mm), combined with still high enough spatial resolution (~14 Rs). Here we address the faint polarization sub-structure and the shape of the jet and counter-jet. Our main objective is the ultra-deep polarization imaging of core and inner twin-jet morphology and the question of intrinsic symmetry/asymmetry. In Spring 2020, M87 will also be observed with the GMVA+ALMA at 86 GHz and the EHT+ALMA at 230 GHz. This facilitates a complete spectral, polarimetric and rotation measure analysis of the jet-base at an unprecedented resolution, in which the proposed global 7mm VLBI will complement the lower frequency coverage.