| We request observations to search for central core images in two gravitational lenses.
Gravitational lenses may include a faint core image, whose brightness depends on the density profile in the central
region: a steeper profile in the central region generates a fainter image. For each system, a detection or upper limit
on the core image flux will determine whether the core is large and relatively shallow, or smaller and steeper.
Confusion of the core image and the lens galaxy in the optical regime requires core image observations to be made
in the radio. The core image is expected to be faint and located 30-100 mas from a much brighter lens image, so the
angular resolution of VLBI and the high sensitivity of the HSA is required. |
