GS032

The nuclear structure in nearby AGN at very high resolution with RadioAstron

Abstract

We request four global-VLBI observing sessions at 18, 6, and 1.3cm to support space-VLBI
observations of nearby radio galaxies within a RadioAstron Key Science Program. This study
will employ RadioAstron perigee imaging to probe the nuclear structure in M87, Cygnus A,
and 3C84 at unprecedented spatial resolution of only a few to few hundred Schwarzschild
radii, thereby directly probing the jet acceleration and collimation region. Transversally
resolving this region can allow direct comparisons with current theoretical models of
magnetohydrodynamic jet formation to be done. We also propose to obtain additional 15 and
43 GHz VLBI images during the periods when the RadioAstron datalink is down. These will
be combined with RadioAstron data to provide matched-resolution spectral images at ultrahigh
resolution. Such data will allow studying the free-free absorbing material in the nuclear
region at a few tens of light-day resolution as well as measuring the magnetic flux density in
the innermost part of the jet. Due to the strongly evolving perigee heigth of the RadioAstron
orbit, the period from July 2013 to June 2014 will be the best possibility for the next three
years to perform imaging observations with the space radio telescope.

Investigators

Name	Institution
Tuomas Savolainen *	Max-Planck-Institut für Radioastronomie; Aalto yliopisto
James Anderson	Deutsches GeoForschungsZentrum
Sang-Sung Lee	Korea Astronomy and Space Science Institute
Bong Won Sohn	Korea Astronomy and Space Science Institute
Monica Orienti	Istituto Nazionale di Astrofisica; Bologna, Universita degli Studi di
Yuri Kovalev	Green Bank Observatory
Thomas Kirchbaum	Max-Planck-Institut für Radioastronomie
Andrei Lobanov	Max-Planck-Institut für Radioastronomie
Steven Tingay	Curtin University of Technology
Gabriele Giovannini	Istituto Nazionale di Astrofisica
Kazuhiro Hada	National Astronomical Observatory of Japan

* indicates the PI