Mass and Light distributions in Clusters of Galaxies - Henry A ...

negligibly contaminated by the cluster (V − i ′ < 0.2). Combining both the
red and blue background populations I get an improved measurement of the
mass profile and derive constraints on the cluster concentration parameter,
clearly excluding low-concentration cold dark matter profiles.
As described in Chapter 3, the work was extended to three more intermediate
redshift clusters, A1703 (z = 0.258), A370 (z = 0.375) and RXJ1347-11
(z = 0.451) imaged with Subaru in at least three bands. With the multiband
data available here, I use the color-color diagram to demonstrate how
the lensing signal can be harnessed to separate cluster members from the
foreground and background populations in a more secure and robust way,
and identify several background galaxy populations of different nature for a
weak lensing measurement. The luminosity functions of these clusters, when
corrected for dilution, all have similar faint-end slopes, α ≃ −1.0, with no
marked faint-end upturn to the magnitude limit of M R ≃ −15.0, but a mild
radial gradient. Here too, for each of our clusters the M/L profile peaks
at intermediate radius, r ≃ 0.2r vir , at a level of 300 − 500(M/L R ) ⊙ , and
then falls steadily towards ∼ 100(M/L R ) ⊙ at the virial radius, similar to
the mean field level. This behavior is likely due to the intrinsic dearth of
late-type galaxies relative to early types nearer the center, whereas for the
E/S0-sequence only a mild radial decline in M/L is found for each cluster.
This can be explained by the continued conversion of disk galaxies into S0
galaxies, via tidal and gas stripping processes. I discuss this behavior in the
context of detailed simulations where predictions for tidal stripping may now
be tested accurately with observations.
The amplitude of weak lensing increases with source redshift, and is
proportional to the lensing distance ratio, D ds /D s , rising steeply behind a
lens and saturating at higher redshift. It provides, in principle, a modelindependent
way of measuring cosmological parameters. Using the multiband
Subaru dataset of the cluster A370, I explore this relation in Chapter
4. Applying the selection methods I developed I further separate and
select from the color-color diagram several background populations of differing
depths (0.6 < z < 3.8), including a prominent sample of distant dropout
galaxies, with little overlap in redshift. I accurately measure their lensing
amplitude, taking account of the radial variation of the weak lensing profile.
I define the depths of the lensed populations with reference to the COSMOS
and GOODS field surveys. The predicted distance-redshift relation is confirmed
for a wide range of cosmological models, albeit without the ability to
distinguish between models with only one cluster. Scaling this result to our
new approved HST /CLASH survey of ∼ 25 massive, relaxed clusters should
provide a useful cosmological constraint on the dark energy equation of state
VI