42 research outputs found
Direct measurement of dark matter halo ellipticity from two-dimensional lensing shear maps of 25 massive clusters
We present new measurements of dark matter distributions in 25 X-ray luminous
clusters by making a full use of the two-dimensional (2D) weak lensing signals
obtained from high-quality Subaru/Suprime-Cam imaging data. Our approach to
directly compare the measured lensing shear pattern with elliptical model
predictions allows us to extract new information on the mass distributions of
individual clusters, such as the halo ellipticity and mass centroid. We find
that these parameters on the cluster shape are little degenerate with cluster
mass and concentration parameters. By combining the 2D fitting results for a
subsample of 18 clusters, the elliptical shape of dark matter haloes is
detected at 7\sigma significance level. The mean ellipticity is found to be e =
0.46 \pm 0.04 (1\sigma), which is in excellent agreement with the standard
collisionless CDM model prediction. The mass centroid can be constrained with a
typical accuracy of ~20" (~50 kpc/h) in radius for each cluster with some
significant outliers, enabling to assess one of the most important systematic
errors inherent in the stacked cluster weak lensing technique, the mass
centroid uncertainty. In addition, the shape of the dark mass distribution is
found to be only weakly correlated with that of the member galaxy distribution.
We carefully examine possible sources of systematic errors in our measurements,
finding none of them to be significant. Our results demonstrate the power of
high-quality imaging data for exploring the detailed spatial distribution of
dark matter (Abridged).Comment: 17 pages, 10 figures, MNRAS in pres
Source Selection for Cluster Weak Lensing Measurements in the Hyper Suprime-Cam Survey
We present optimized source galaxy selection schemes for measuring cluster
weak lensing (WL) mass profiles unaffected by cluster member dilution from the
Subaru Hyper Suprime-Cam Strategic Survey Program (HSC-SSP). The ongoing
HSC-SSP survey will uncover thousands of galaxy clusters to . In
deriving cluster masses via WL, a critical source of systematics is
contamination and dilution of the lensing signal by cluster {members, and by
foreground galaxies whose photometric redshifts are biased}. Using the
first-year CAMIRA catalog of 900 clusters with richness larger than 20
found in 140 deg of HSC-SSP data, we devise and compare several
source selection methods, including selection in color-color space (CC-cut),
and selection of robust photometric redshifts by applying constraints on their
cumulative probability distribution function (PDF; P-cut). We examine the
dependence of the contamination on the chosen limits adopted for each method.
Using the proper limits, these methods give mass profiles with minimal dilution
in agreement with one another. We find that not adopting either the CC-cut or
P-cut methods results in an underestimation of the total cluster mass
() and the concentration of the profile (). The level of
cluster contamination can reach as high as at
Mpc/ for low-z clusters without cuts, while employing either the P-cut or
CC-cut results in cluster contamination consistent with zero to within the 0.5%
uncertainties. Our robust methods yield a detection of the
stacked CAMIRA surface mass density profile, with a mean mass of
.Comment: 19 pages, 4 tables, 12 figures, accepted to PASJ special issu
Suzaku Observation of Abell 1689: Anisotropic Temperature and Entropy Distributions Associated with the Large-Scale Structure
(Abridged) We present results of Suzaku observations of the intracluster
medium (ICM) in Abell 1689, combined with complementary analysis of the SDSS
data and weak and strong lensing analysis of Subaru/Suprime-Cam and HST/ACS
observations. Faint X-ray emission from the ICM around the virial radius is
detected at 4.0 sigma significance. We find anisotropic gas temperature and
entropy distributions in cluster outskirts correlated with large-scale
structure of galaxies. The high temperature and entropy region in the
northeastern (NE) outskirts is connected to an overdense filamentary structure.
The outskirt regions in contact with low density void environments have low gas
temperatures and entropies, deviating from hydrostatic equilibrium. These
results suggest that thermalization of the ICM occurs faster along the
filamentary structures than the void regions. A joint X-ray and lensing
analysis shows that the hydrostatic mass is of spherical lensing
one but comparable to a triaxial halo mass within errors in 0.6r_{2500} \simlt
r \simlt 0.8r_{500}, and that it is significantly biased as low as \simlt60%
within , irrespective of mass models. The thermal gas pressure
within is, at most, --60% of the total pressure to balance
fully the gravity of the spherical lensing mass, and --40% around the
virial radius. Although these constitute lower limits when one considers the
possible halo triaxiality, these small relative contributions of thermal
pressure would require additional sources of pressure, such as bulk and/or
turbulent motions.Comment: 24 pages, 15 figures, 9 tables. Accepted for publication in Ap
A Systematic Search of Distant Superclusters with the Subaru Hyper Suprime-Cam Survey
Superclusters, encompassing environments across a wide range of
overdensities, can be regarded as unique laboratories for studying galaxy
evolution. Although numerous supercluster catalogs have been published, none of
them goes beyond redshift . In this work, we adopt a physically
motivated supercluster definition, requiring that superclusters should
eventually collapse even in the presence of dark energy. Applying a
friends-of-friends (FoF) algorithm to the CAMIRA cluster sample constructed
using the Subaru Hyper Suprime-Cam survey data, we have conducted the first
systematic search for superclusters at and identified
supercluster candidates over an area of 1027 deg. The FoF algorithm is
calibrated by evolving -body simulations to the far future to ensure high
purity. We found that these high- superclusters are mainly composed of
clusters, suggesting the limit of gravitationally bound structures in the
younger Universe. In addition, we studied the properties of the clusters and
brightest cluster galaxies (BCGs) residing in different large-scale
environments. We found that clusters associated with superclusters are
typically richer, but no apparent dependence of the BCG properties on
large-scale structures is found. We also compared the abundance of observed
superclusters with mock superclusters extracted from halo light cones, finding
that photometric redshift uncertainty is a limiting factor in the performance
of superclusters detection.Comment: Submitted to ApJ. 29 pages, 22 figures, 6 table
Clinical evaluation was examined between mixed type barium sulfate suspensions "BarytgenHD" and "Barytgen"
混合粒子型硫酸バリウムバリトゲンHD200w/v%懸濁液について,バリトゲン160w/v%懸濁液と比較検討を行った。懸濁液安定性は両者共良かった。臨床評価においては,付着性,胃小区描出能は同程度であり,辺縁の描出能は良かったが凝集・ムラ付き,気泡は多くみられ懸濁液濃度について検討を加える必要があると考える。飲み易さは,バリトゲンHD200w/v%懸濁液のほうが濃度が高いのにもかかわらず飲み易く好評であった。Both barium sulfate suspensions, Barytgen HD and Barytgen, had good stability. Although significant difference was not abserved in coating and visualization of gastric area, BarytgenHD showed better marginal visualization of gastric margin. Further study is needed to improve the visualization of sticky coating of gastric mucosa and many bubbles. BarytgenHD was easily to drink instead of high density barium sulfate suspensions