VLBA14B-516

A combined 1.3mm and 3mm VLBI study of jet genesis in M87 - revised version

Abstract

We propose target of opportunity global 3mm-VLBI observations of M87 vital to enhance a scheduled global 1.3mm-VLBI experiment with the EHT in March, 2015. We submit this proposal as ToO, since scheduling and details of the 1.3mm-VLBI run were not known at the previous submission deadline.
Observations could be scheduled either via HSA or GMVA.
The purpose is to obtain a high quality 3mm-VLBI image, to help interpreting results from 1mm-VLBI, which is more sensitivity and
uv-coverage limited.
With the combined 3mm/1mm data we aim at a coherent understanding of
the event horizon-scale structure in M87, and in particular of the jet launching region on scales from about 3-100 Schwarzschild radii.
The proposed observations will allow us to:
(1) determine size and shape of the jet base versus frequency down to about 3 Rs;
(2) study spectral index along the northern and southern
jet sheath and in core;
3) determine VLBI component spectra and their magnetic field strength;
4) test if core and inner jet sheath are polarized; and
5) constrain theoretical GRMHD modeling (eg. BP vs. BZ of jet launching by accurate observational data.
We note that combined 3mm/1.3mm observation can only be done once per year.

Investigators

Name	Institution
Vincent Fish	Haystack Observatory
Shep Doeleman	Haystack Observatory
Michael Lindqvist	Chalmers University of Technology
Pablo de Vicente	Yebes, Centro Astronómico de
David Hughes	Astrofísica, Óptica y Electrónica, Instituto Nacional de
Masanori Nakamura	Academia Sinica; National Institute of Technology, Hachinohe College
Keiichi Asada	Academia Sinica
Michael Bremer	Institut de Radio Astronomique Millimétrique
Jose L. Gomez	Andalucía, Instituto de Astrofísica de
R. Craig Walker	National Radio Astronomy Observatory
Thomas Krichbaum	Max-Planck-Institut für Radioastronomie
Rusen Lu *	Max-Planck-Institut für Radioastronomie; Shanghai Astronomical Observatory, CAS

* indicates the PI