G17B003

Ultra-Deep Polarization Imaging of the Twin-Jet Structure in M87

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, which is a sweet spot. 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 2018 M87 will also be observed with RadioAstron at
22 GHz, 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 bridge the gap in the
frequency coverage.

Investigators

Name	Institution
GBT Operator	Green Bank Observatory
GBT Operator	Green Bank Observatory
Thomas Kirchbaum	Max-Planck-Institut für Radioastronomie
Rusen Lu	Max-Planck-Institut für Radioastronomie
Uwe Bach	Max-Planck-Institut für Radioastronomie
Jose L. Gomez	Andalucía, Instituto de Astrofísica de
Sang-Sung Lee	Korea Astronomy and Space Science Institute
Monika Moscibrodzka	Nijmegen, Radboud Universiteit
Bong Won Sohn	Korea Astronomy and Space Science Institute
Pablo de Vicente	Yebes, Centro Astronómico de
R. Craig Walker	National Radio Astronomy Observatory
Tony Zensus	National Radio Astronomy Observatory; Max-Planck-Institut für Radioastronomie
Jae-Young Kim *	Max-Planck-Institut für Radioastronomie; Kyungpook National University

* indicates the PI