GM073

Testing galaxy formation on the smallest scales with VLBI

Abstract

We request 27 hrs Global VLBI observations at 5 GHz of the gravitational lenses MG
J0751+2716 and B1938+666. The aim of these observations is to image the extended
gravitational arcs of the radio-loud jets at mas resolution. These data will be used to find
evidence of low mass substructure (less than 10^8 solar mass dark matter haloes) hosted in
the massive ~10^12 solar mass lensing galaxies. Low mass substructure would be detected
through the small perturbations that they produce on the extended gravitational arcs. The
excellent resolution and sensitivity of the proposed observations could image the small radius
(~5 mas) Einstein rings that substructure is expected to produce. The detection of low mass
substructure in the lensing galaxy would strongly constrain cold dark matter models of galaxy
formation and give the most stringent constraints to the low-end of the substructure mass
function.

Investigators

Name	Institution
David Lagattuta	California at Davis, University of
Chris Fassnacht	California at Davis, University of
Leon Koopmans	Kapteyn Astronomical Institute
Matthew Auger	California at Davis, University of; Cambridge, University of
Simona Vegetti	Massachusetts Institute of Technology
Cristiana Spingola	Kapteyn Astronomical Institute; Istituto Nazionale di Astrofisica; Bologna, Università degli Studi di
John McKean *	Netherlands Institute for Radio Astronomy; Kapteyn Astronomical Institute

* indicates the PI