VLBA18A-270

Quantifying dark matter substructure in gravitational lens galaxies

Abstract

We request 12 + 6 hrs of HSA observations at 22 and 15 GHz to map the extended images from the gravitational lenses JVAS B1938+666 and JVAS B1422+231 at sub-mas angular resolution. These data will be used to confirm the detection of low mass substructure (< 10^8 solar mass dark matter haloes) hosted within the massive ~10^12 solar mass lensing galaxies. Low mass substructure would be detected through the small perturbations that they produce on the extended gravitationally lensed images. The excellent resolution and sensitivity of the proposed observations would image the small radius (~3 mas) mini-arcs that substructure is expected to produce, or at least detect the sub-mas astrometric shifts in the sub-components within the individual images. These two gravitational lenses already show strong evidence from radio and infra-red data of substructure at low mass-scales that directly challenge warm dark matter models. These new observations will confirm that substructure is indeed the cause, or demonstrate that prior assumptions about propagation effects or finite sources sizes being negligible are incorrect.

Investigators

Name	Institution
Matthew Auger	California at Davis, University of; Cambridge, University of
Christopher Fassnacht	California at Davis, University of
Leon Koopmans	Kapteyn Astronomical Institute
Simona Vegetti	Max-Planck-Institut für Astrophysik
Cristiana Spingola	Kapteyn Astronomical Institute; Istituto Nazionale di Astrofisica; Bologna, Universita degli Studi di
John McKean *	Netherlands Institute for Radio Astronomy; Kapteyn Astronomical Institute
GBT Operator	Green Bank Observatory

* indicates the PI