NOAO > Observing Info > Approved Programs > 2012A-0382
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NOAO > Observing Info > Approved Programs > 2012A-0382 |
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PI: Ian P. Dell'Antonio, Brown University, ian@het.brown.edu
Address: Physics Department, Box 1843, 182 Hope Street, Providence, RI 02912, USA
CoI: Richard I. Cook, Brown University
Title: A Strong Lensing Measurement in the Anomalous Cluster Abell 781D
Abstract:
We propose to obtain the redshift of the strongly lensed arc in
Abell 781D, the western component in the complex of clusters that is
Abell 781. This will allow us to measure the mass of the central region
of this peculiar cluster. Although both the X-ray emission and the
velocity dispersion of galaxies in the cluster suggest a significant
mass, three weak lensing measurements of the cluster, made with
different telescopes and different source depths, all consistently show
a much lower signal. It is essential to determine the origin of
systematic errors and biases in weak lensing mass estimates for the
successful calibration of mass-observables in future cosmological
surveys.
To help unravel the mystery of the mass discrepancy in Abell 781D,
we need to have an accurate mass scale measurement of the cluster.
Fortunately there is a large blue strong lensing arc near the central
galaxy of the cluster, however an optical spectrum of the arc revealed
no identifiable emission line features. We therefore request GNIRS
spectroscopy to obtain the redshift of the arc to complete the mass
calibration of the cluster. It will then be possible to measure the
mass density of the central region via strong lensing analysis.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2012A-0382 |
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