We use Keck laser guide star adaptive optics imaging and exploit the magnifying effects of strong gravitational lensing (the effective resolution is FWHM ~ 200 pc) to investigate the sub-kpc scale of an intermediate-redshift (z = 0.63) massive early-type galaxy being lensed by a foreground early-type galaxy; we dub this class of strong gravitational lens systems EELs, e.g., early-type/early-type lenses. We find that the background source is massive (M* = 10^{10.9} M_sun) and compact (r_e = 1.1 kpc), and a two-component fit is required to model accurately the surface brightness distribution, including an extended low-surface-brightness component. This extended component may arise from the evolution of higher-redshift `red nuggets' or may already be in place at z ~ 2 but is unobservable due to cosmological surface brightness dimming.
@article{arxiv.1011.0993,
title = {A Compact Early-type Galaxy at z = 0.6 Under a Magnifying Lens: Evidence For Inside-out Growth},
author = {M. W. Auger and T. Treu and B. J. Brewer and P. J. Marshall},
journal= {arXiv preprint arXiv:1011.0993},
year = {2015}
}