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Astronomy Tea Talks at Caltech

Mondays, Hameetman auditorium (Cahill)
Tea:  4.00pm
Talk: 4.15pm

Organized by:

2009 - 2010 season:
12 October 2009 Assaf Horesh (Tel Aviv)

'New Results for Giant Arc Statistics in ~100 Clusters Observed with HST'

Gravitational lensing is frequently used to map the evolution of
cluster mass profiles, ellipticities, and substructure. One approach is
to perform detailed modeling of individual clusters using strong and
weak lensing, but this is generally suited
only to deep data for individual clusters that exhibit numerous lensed
images, and the results may not be representative of the majority of
clusters. A complementary approach is to measure the statistics of
lensed arcs in large samples of clusters. Over the past decade, a debate
has gone on about the nature of cluster samples selected by different
methods, and about whether or not real clusters are highly more efficient
producers of arcs than expected from theory. I will present an
analysis of the arc statistics in a sample of ~100 galaxy clusters
observed with the HST/ACS. X-ray selected clusters
are much more efficient lenses than optically-selected clusters of
similar optical luminosity, showing that optical selection yields
lower-mass, perhaps marginally bound, structures. I will also present
our past and in-progress comparison of observed arc statistics with
simulations that aim to include all the theoretical and observational
aspects of the problem.

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Last modified on 20th Jul 2011 by Dominik A. Riechers.  

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