1,702 research outputs found
The Mean and Scatter of the Velocity Dispersion-Optical Richness Relation for maxBCG Galaxy Clusters
The distribution of galaxies in position and velocity around the centers of
galaxy clusters encodes important information about cluster mass and structure.
Using the maxBCG galaxy cluster catalog identified from imaging data obtained
in the Sloan Digital Sky Survey, we study the BCG-galaxy velocity correlation
function. By modeling its non-Gaussianity, we measure the mean and scatter in
velocity dispersion at fixed richness. The mean velocity dispersion increases
from 202+/-10 km/s for small groups to more than 854+/-102 km/s for large
clusters. We show the scatter to be at most 40.5+/-3.5%, declining to
14.9+/-9.4% in the richest bins. We test our methods in the C4 cluster catalog,
a spectroscopic cluster catalog produced from the Sloan Digital Sky Survey DR2
spectroscopic sample, and in mock galaxy catalogs constructed from N-body
simulations. Our methods are robust, measuring the scatter to well within
one-sigma of the true value, and the mean to within 10%, in the mock catalogs.
By convolving the scatter in velocity dispersion at fixed richness with the
observed richness space density function, we measure the velocity dispersion
function of the maxBCG galaxy clusters. Although velocity dispersion and
richness do not form a true mass-observable relation, the relationship between
velocity dispersion and mass is theoretically well characterized and has low
scatter. Thus our results provide a key link between theory and observations up
to the velocity bias between dark matter and galaxies.Comment: 25 pages, 15 figures, 2 tables, published in Ap
Let us ignore the most important feature of the book
First student printing, Edwin Grabhorn on The Book, 1944-5https://repository.wellesley.edu/bookartsephemera/1001/thumbnail.jp
Estimates of in situ Larval Development Time for the Lobster, Homarus Americanus
Larval development time is a critical factor in assessing the potential for larval transport, mortality. and subsequently, the connectivity of marine populations through larval exchange. Most estimates of larval duration are based on laboratory studies and may not reflect development times in nature. For larvae of the American lobster (Homarus americanus), temperature-dependent development times have been established in previous laboratory studies. Here, we used the timing of seasonal abundance curves for newly hatched larvae (stage 1) and the final plankonic instar (postlarva), coupled with a model of temperature-dependent development to assess development time in the field. We were unable to reproduce the timing of the seasonal abundance curves using laboratory development rates in our model. Our results suggest that larval development in situ may be twice as fast as reported laboratory rates. This will result in reduced estimates of larval transport potential, and increased estimates of instantaneous mortality rate and production
Daya Terima Dan Kadar Betakaroten Donat Substitusi Labu Kuning
Vitamin A defi ciency in Indonesia is still unresolved, especially in children. Pumpkin is a type of tubers and a local food product that contains high beta-carotene. It is also potential to be used as a substitution for snacks which favored by children such as donuts. The purpose of this study was to determine the acceptability and beta-carotene level of pumpkin donut substitution. This research was true experimental for product development and quasi experimental for acceptability with a completely randomized design, 6 repetitions on one control formula (F0) and 3 modifi cation formula (F1, F2, F3) with additional of pumpkin. Panelist consists of 4 people as limited panelists and 30 people as non trained panelists. The difference of acceptability was analyze using Friedman test and continued with Wilcoxon Signed Rank Test if it shows a signifi cant difference. The level of beta-carotene was analyze using spectrophotometer. The result of this study showed the best acceptability found in formula 3 (with 40% addition of pumpkin) with an average value of 2,28 and beta-carotene level of was 0,139 ppms. Formula 3 donut have a good acceptability and also contains higherbeta-carotene than commercial donuts, so it is potential as an alternative healthy snack for schoolchildren
Cross-correlation Weak Lensing of SDSS galaxy Clusters II: Cluster Density Profiles and the Mass--Richness Relation
We interpret and model the statistical weak lensing measurements around
130,000 groups and clusters of galaxies in the Sloan Digital Sky Survey
presented by Sheldon et al. 2007 (Paper I). We present non-parametric
inversions of the 2D shear profiles to the mean 3D cluster density and mass
profiles in bins of both optical richness and cluster i-band luminosity. We
correct the inferred 3D profiles for systematic effects, including non-linear
shear and the fact that cluster halos are not all precisely centered on their
brightest galaxies. We also model the measured cluster shear profile as a sum
of contributions from the brightest central galaxy, the cluster dark matter
halo, and neighboring halos. We infer the relations between mean cluster virial
mass and optical richness and luminosity over two orders of magnitude in
cluster mass; the virial mass at fixed richness or luminosity is determined
with a precision of 13% including both statistical and systematic errors. We
also constrain the halo concentration parameter and halo bias as a function of
cluster mass; both are in good agreement with predictions of LCDM models. The
methods employed here will be applicable to deeper, wide-area optical surveys
that aim to constrain the nature of the dark energy, such as the Dark Energy
Survey, the Large Synoptic Survey Telescope and space-based surveys
Proceedings of the North American Blueberry Research and Extension Workers Meeting, 2018 Orono, Maine
The 2018, the North American Blueberry Research and Extension Workers (NABREW) Conference took place August 12-15 at the Wells Conference Center at the University of Maine in Orono. The meeting was conducted by the University of Maine Cooperative Extension, and a welcome was provided by the president of the University of Maine and UMM, Dr. Joan Ferrini-Mundy. This is the second time that this national conference has been held in Maine; the first was in 1966. This year more than 74 participants from 13 states and four other countries - Norway, Canada, Mexico and New Zealand - attended the conference
Weak-lensing calibration of a stellar mass-based mass proxy for redMaPPer and Voronoi Tessellation clusters in SDSS Stripe 82
We present the first weak lensing calibration of , a new galaxy
cluster mass proxy corresponding to the total stellar mass of red and blue
members, in two cluster samples selected from the SDSS Stripe 82 data: 230
redMaPPer clusters at redshift and 136 Voronoi Tessellation
(VT) clusters at . We use the CS82 shear catalog and stack
the clusters in bins to measure a mass-observable power law
relation. For redMaPPer clusters we obtain , . For VT clusters, we find
, and , for a low and a high redshift bin, respectively. Our results are
consistent, internally and with the literature, indicating that our method can
be applied to any cluster finding algorithm. In particular, we recommend that
be used as the mass proxy for VT clusters. Catalogs including
measurements will enable its use in studies of galaxy evolution
in clusters and cluster cosmology.Comment: Updated to be consistent with the published versio
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