AAS 207th Meeting, 8-12 January 2006
Session 200 Gravity: Lenses, Dark Matter and Waves
Oral, Thursday, 2:00-3:30pm, January 12, 2006, Ballroom/Salon 2

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[200.03] An Automated Search for Gravitational Lenses in the HST Imaging Archive

P.J. Marshall (KIPAC), L.A. Moustakas (JPL), D.W. Hogg (NYU), M. Bradac (KIPAC), C.D. Fassnacht (UCDavis), R.D. Blandford (KIPAC)

Statistical samples of galaxy-scale strong gravitational lenses are powerful probes of the CDM model, offering insights into the halo density profiles and occupation distributions unavailable to other methods. The cross-section for strong lensing in the Universe is dominated by massive elliptical galaxies; the typical lensed source is a faint blue star-forming galaxy. Such lenses, with their characteristic patterns of multiple images, arcs and rings are readily recognised by experienced researchers visually inspecting multi-filter optical images - here we investigate the possibility of having a software ``robot'' perform the same task, and show results of comparative trials on HST archive data. Two new gravitational lenses are presented.

We discuss the implications of this study for imaging surveys that will eventually cover significant fractions of the sky. Elliptical galaxies have a number density of several thousand per square degree: even a present-day HST sky coverage of 2 square degrees yields a sample of ~ 104 galaxies, to be distilled down to a few tens of lenses. Robots such as this one will be essential in analysing the imaging dataset from future telescopes: the SNAP strong lens survey should increase the number of known galaxy-scale lenses by some three orders of magnitude.

This work is supported by HST grant HST-AR-10676.

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