11246(  1) - 03/30/07 11:04  - [  1]

                  HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11246

Version: 1    Check-in Time: 30-Mar-2007 15:04:41       STScI Edit Number: 0

Title
Evolution in the Dark Matter Properties of Strong Lenses through Weak Lensing
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Type             Cycle     Parallel Pointing Tolerance
AR               16        <none>
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Investigators
                                                                                     Contact?
    PI: Prof. Christopher Fassnacht       University of California - Davis
   CoI: Mr. David Lagattuta               University of California - Davis              N
   CoI: Mr. Matthew Auger                 University of California - Davis              N
   CoI: Dr. Raphael Gavazzi               University of California - Santa Barbara      N
   CoI: Dr. Philip J. Marshall            University of California - Santa Barbara      N
   CoI: Prof. Tommaso L. Treu             University of California - Santa Barbara      N
   CoI: Prof. Leon Koopmans               Kapteyn Astronomical Institute                N
   CoI: Dr. Marusa Bradac                 Stanford University                           N

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Abstract

To fully exploit the information on the dark matter mass profiles of galaxies gained
from weak lensing and to tie this to their inner regions where baryons play an
important role, we propose to investigate a special sample of galaxies, namely
strong gravitational lenses. These systems are excellent targets for weak lensing
studies because the Einstein ring radii provide a direct measurement of the
projected mass at very small scales -- information that is not available for most
galaxy samples. This project is especially well suited for an archival program
because nearly every strong lens system has been imaged with HST, and the data are
public. What makes this project stand out is that we can compare strong lens samples
at moderate redshift (median z ~ 0.6) and lower redshift (median z ~ 0.2) and can,
thus, use the full power of combining strong and weak lensing in our investigation
of evolutionary effects over this timescale. We will use our samples to (1) measure
the average mass profile of the sample to R ~ 300 kpc/h, (2) quantify the evolution
of stellar mass and virial mass-to-light ratios, and (3) investigate whether the
``bulge-halo conspiracy'', whereby the CDM profiles of galaxies are NFW but the
total (baryonic plus CDM) mass profile are isothermal out to ~ 300 kpc/h, is in
place at higher redshifts.
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