From: Eric Linder (evlinder@lbl.gov)
Date: Thu Jan 26 2006 - 08:32:04 PST
Hi Joe,
Your text on strong lensing looks good. I particularly liked the
ending, which unfortunately is mostly cut in your truncated version.
If the short version is used, I'd suggest changing the last sentence
"Detailed modeling..." to
"This enables high high fidelity reconstructions of the dark
matter distribution,
similar to the recent analysis of Abell 1689 by the ACS GTO team
(Broadhurst et al. 2005), but for clusters at $z \gtrsim 1$. Our
unprecedented deep
imaging survey of high redshift clusters will allow us to address the
dark matter behavior in detail."
Cheers,
Eric
On Jan 25, 2006, at 12:03 AM, Joseph Hennawi wrote:
> Hi All,
>
> Below is a revision of the strong lensing text. I think it is
> stronger, but unfortunately it is not much shorter. How hard
> pressed are we for space?
>
> If anybody has found any new giant arcs in their HST images please
> report them to me now so we can mention them in the text. The tally
> so far is 1 (RCS 0220-03), plus another arc in
> one other cluster (not sure which one), but I believe this was
> already discovered in previous HST imaging that was not part of
> this program. If there are other known lensing clusters on the
> target list for cycle 14 or cycle 15, let me know. Currently the
> only one I know of is RCS2319+0038 at z=0.91. These should be
> mentioned.
>
>
> \SUBSECTION{Strong lenses at $z \gs 1$}
>
> Does the currently popular $\Lambda$CDM cosmological model explain the
> detailed distribution of dark matter in galaxy clusters? Strong
> gravitational lensing by clusters is a powerful test of this model,
> probing the rare, highest mass concentrations in the Universe, where
> the dark matter density is highest. However, the
> frequency of giant arcs observed in the Red-Sequence Cluster survey
> (RCS) (Gladders \etal 2003) highlights potential conflicts with the
> predictions of $\Lambda$CDM, particularly at high redshifts.
> While $\Lambda$CDM predicts that the distribution of
> lensing clusters should be peaked at $z \sim 0.4$, {\em all} the
> lensing
> clusters in the RCS sample are at $z\gtrsim 0.7$. In addition, the
> presence of several high redshift clusters with multiple arcs at large
> Einstein radii, have led many to speculate that these systems might
> constitute a distinct population of `superlenses', with extremely
> large lensing cross sections (Gladders et al. 2003; Dalal et al. 2004;
> but see also Ho \& White 2005) -- whereas $\Lambda$CDM makes no such
> prediction.
>
> Our cycle 14 sample already contains 2 (?) new giant arc systems
> lensed
> by $z \gtrsim 1$ clusters, nearly doubling the number known. These are
> in addition to the known high redshift lensing cluster RCS2319+0038
> (z=0.91), which is on our cycle 14 target list but not yet
> observed. The superb image quality delivered by the ACS dramatically
> increases the number of the number of faint, low surface brightness
> arcs and image families detectable. This will enable detailed modeling
> of the distorted image positions, resulting in high fidelity mass
> reconstructions which will measure the distribution of dark matter,
> similar to the recent exciting analysis of Abell 1689 by the ACS GTO
> team (Broadhurst et al. 2005), but for clusters at $z \gtrsim 1$.
> Does $\Lambda$CDM predict the correct mass distributions at high
> redshift? Or could there be new physics lurking in the dark matter
> sector on small scales or high overdensities? Our unprecedented deep
> imaging survey of high redshift clusters will allow us to address this
> fundamental question.
>
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