1,038 research outputs found
A magnified glance into the dark sector: probing cosmological models with strong lensing in A1689
In this paper we constrain four alternative models to the late cosmic
acceleration in the Universe: Chevallier-Polarski-Linder (CPL), interacting
dark energy (IDE), Ricci holographic dark energy (HDE), and modified polytropic
Cardassian (MPC). Strong lensing (SL) images of background galaxies produced by
the galaxy cluster Abell are used to test these models. To perform this
analysis we modify the LENSTOOL lens modeling code. The value added by this
probe is compared with other complementary probes: Type Ia supernovae (SNIa),
baryon acoustic oscillations (BAO), and cosmic microwave background (CMB). We
found that the CPL constraints obtained of the SL data are consistent with
those estimated using the other probes. The IDE constraints are consistent with
the complementary bounds only if large errors in the SL measurements are
considered. The Ricci HDE and MPC constraints are weak but they are similar to
the BAO, SNIa and CMB estimations. We also compute the figure-of-merit as a
tool to quantify the goodness of fit of the data. Our results suggest that the
SL method provides statistically significant constraints on the CPL parameters
but weak for those of the other models. Finally, we show that the use of the SL
measurements in galaxy clusters is a promising and powerful technique to
constrain cosmological models. The advantage of this method is that
cosmological parameters are estimated by modelling the SL features for each
underlying cosmology. These estimations could be further improved by SL
constraints coming from other galaxy clusters.Comment: 13 pages, 5 figures, accepted for publication in Ap
Gravitational lensing and dynamics in SL2S\,J02140-0535: Probing the mass out to large radius
We aim to probe the mass of SL2S\,J02140-0535, a galaxy group at = 0.44
from the Strong Lensing Legacy Survey (SL2S). We combine strong lensing
modeling and dynamical constraints. The strong lensing analysis is based on
multi-band HST/ACS observations exhibiting strong lensing features that we have
followed-up spectroscopically with VLT/FORS2. To constrain the scale radius of
an NFW mass profile that cannot be constrained by strong lensing, we propose a
new method by taking advantage of the large-scale dynamical information
provided by VLT/FORS2 and KECK/LRIS spectroscopy of group members. In constrast
to other authors, we show that the observed lensing features in
SL2S\,J02140-0535 belong to different background sources: one at = 1.7
0.1 produces three images, while the other at = 1.023 0.001 has
only a single image. Our unimodal NFW mass model reproduces these images very
well. It is characterized by a concentration parameter = 6.0
0.6, which is slightly greater than the value expected from CDM
simulations for a mass of M 1 10 M_{\sun}.
The spectroscopic analysis of group members also reveals a unimodal structure
that exhibits no evidence of merging. We compare our dynamic mass estimate with
an independent weak-lensing based mass estimate finding that both are
consistent. Our combined lensing and dynamical analysis of SL2S\,J02140-0535
demonstrates the importance of spectroscopic information in reliably
identifying the lensing features. Our findings argue that the system is a
relaxed, massive galaxy group where mass is traced by light. This work shows a
potentially useful method for constraining large-scale properties inaccessible
to strong lensing, such as the scale radius of the NFW profile.Comment: Accepted for publication in A&
The abundance of Bullet-groups in LCDM
We estimate the expected distribution of displacements between the two
dominant dark matter (DM) peaks (DM-DM displacements) and between DM and
gaseous baryon peak (DM-gas displacements) in dark matter halos with masses
larger than Msun/h. We use as a benchmark the observation of SL2S
J08544-0121, which is the lowest mass system ( Msun/h)
observed so far featuring a bi-modal dark matter distribution with a dislocated
gas component. We find that % of the dark matter halos with
circular velocities in the range 300 km/s to 700 km/s (groups) show DM-DM
displacements equal or larger than kpc/h as observed in SL2S
J08544-0121. For dark matter halos with circular velocities larger than 700
km/s (clusters) this fraction rises to 70 10%. Using the same simulation
we estimate the DM-gas displacements and find that 0.1 to 1.0% of the groups
should present separations equal or larger than kpc/h corresponding
to our observational benchmark; for clusters this fraction rises to (7
3)%, consistent with previous studies of dark matter to baryon separations.
Considering both constraints on the DM-DM and DM-gas displacements we find that
the number density of groups similar to SL2S J08544-0121 is Mpc, three times larger than the estimated value for clusters.
These results open up the possibility for a new statistical test of LCDM by
looking for DM-gas displacements in low mass clusters and groups.Comment: 6 pages, 3 figures, accepted for publication in ApJ Letter
Comparison of price between a healthy and unhealthy diet in the Metropolitan Region, Chile
Indexación: Scopus; Scielo.Obesity remains a serious public health problem worldwide and in Latin America. The implementation of dietary guidelines is a strategy used in Chile and other Latin-American countries to promote healthy eating habits. Evidence from studies in US and Europe suggests that healthy eating patterns have a higher price compared to unhealthy food options. However, this has not been evaluated in Chile. Our goal was to compare the price and relation to energetic density of a healthy diet (HD) that follows the Chilean dietary with an unhealthy diet (UD) in the Metropolitan Region (MR), the most densely populated demographical division in Chile. The HD was obtained from the publication "Cocinasaludable: comoincluir 5 porciones de frutas y verduras por dia", a book of recipessponsored by theChilean governmentto promote intake of fruits and vegetables that fulfills the Chilean dietary guidelines. The UD was obtained by replacing recipesand food items from the DS with processed foods and recipes typically consumed in Chile. The price database was compiled from databases of the Chilean Government and on-line retailers at MR. The UD has higher energy density, has higher energy from fats and a lower healthy eating index compared with the HD. Price analysis indicated an inverse relation between caloric density and price for food groups and that the UD has an overall lower price compared to the HD. Our results suggest that the higher price of a HD in compliance with the Chilean dietary guidelines could hinder their implementation in the MR, and the transition towards healthy eating habits among its population.http://www.scielo.org.ve/scielo.php?script=sci_arttext&pid=S0004-0622201600040000
SARCS strong lensing galaxy groups: I - optical, weak lensing, and scaling laws
We present the weak lensing and optical analysis of the SL2S-ARCS (SARCS)
sample of strong lens candidates. The sample is based on the Strong Lensing
Legacy Survey (SL2S), a systematic search of strong lensing systems in the
photometric Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). The SARCS
sample focuses on arc-like features and is designed to contain mostly galaxy
groups. We briefly present the weak lensing methodology that we use to estimate
the mass of the SARCS objects. Among 126 candidates, we obtain a weak lensing
detection for 89 objects with velocity dispersions of the Singular Isothermal
Sphere mass model ranging from 350 to 1000 km/s with an average value of
600km/s, corresponding to a rich galaxy group (or poor cluster). From the
galaxies belonging to the bright end of the group's red sequence (M_i<-21), we
derive the optical properties of the SARCS candidates. We obtain typical
richnesses of N=5-15 galaxies and optical luminosities of L=0.5-1.5e+12 Lsol
(within a radius of 0.5 Mpc). We use these galaxies to compute luminosity
density maps, from which a morphological classification reveals that a large
fraction of the sample are groups with a complex light distribution, either
elliptical or multimodal, suggesting that these objects are dynamically young
structures. We finally combine the lensing and optical analyses to draw a
sample of 80 most secure group candidates, i.e. weak lensing detection and
over-density at the lens position in the luminosity map, to remove false
detections and galaxy-scale systems from the initial sample. We use this
reduced sample to probe the optical scaling relations in combination with a
sample of massive galaxy clusters. We detect the expected correlations over the
probed range in mass with a typical scatter of 25% in the SIS velocity
dispersion at a given richness or luminosity, making these scaling laws
interesting mass proxie
The Effect of the Minimum Wage on the Average Wage in France (in French)
This study investigates the impact of minimum wage (SMIC) increases on the average wage in France. We use two series of average wage: the average hourly blue-collar wage rate (SHBO) and the average wage per capita (SMPT). We combine these series with aggregate data for the overall economy over four decades from 1970 to 2009, going from the SMIC first implementation (in 1970) to the change in the annual calendar of mandatory increases (in 2009) from the 1st of July to the 1st of January by the law of the 3rd December 2008. We provide three original contributions with respect to the existing literature. First, our study is based on data from a much longer period of time which gives us more information. Second, the models we estimate allow for a very gradual impact of the minimum wage on the average wage, while previous studies often assumed only an immediate impact. Third, we differentiate the impact of minimum wage increases on the average wage by distinguishing between the effects of each of the three sources of increase. Our results confirm the advantages of this approach. Because of the discretionary increases of the minimum wage from the government (the so-called “coup de pouces”), the minimum wage increased more rapidly than the average wage over the period 1970-2009. Our estimates suggest that the impact on the average wage of minimum wage increases is strong. This impact is larger than in previous studies because our models take into account the existence of dynamic diffusion effects. Finally, minimum wage increases related to the legal indexation to half of the increase in the purchasing power of the SHBO have a large effect on the SHBO itself. This result suggests that a feedback effect between the minimum wage and the SHBO is possible and could trigger the dynamics between these series. As a consequence of the legal system of revaluation of the minimum wage and of the impact of these increases on the average wage, France is probably one of the industrialized countries where competitiveness is the most threatened by inflation volatility.Minimum Wage, Average Wage, France.
Main Polar Metabolites from Leaves of the Native Andean Species Jungia rugosa Less (Asteraceae)
The ethanolic extract of Jungia rugosa Less, a popular Andean species belonging to the family Asteraceae, was characterized chemically. The extract was deprived of chlorophyll by solid-phase extraction, using Diaion Hp-20 resin as solid phase, and eluting with a mixture of EtOH/H2O according to a decreasing polarity gradient. The chlorophyll-free extract was then repeatedly fractionated by open column chromatography in normal phase and preparative thin layer chromatography. Two main metabolites were finally purified and identified through structure elucidation. Nuclear magnetic resonance spectroscopy (NMR) and electrospray ionization-mass spectrometry (ESI-MS) were the 2 techniques used for analysis. The identified metabolites were coumarins: (1) umbelliferone and (2) coumarin-5- methyl-4α-glucoside. Compound 1 is known in the literature for having anti-inflammatory, antihyperglycemic, and antitumor activities. Compound 2 has not been described before for this botanical genus and its pharmacological effects are still uninvestigated.
Keywords: Jungia rugosa, umbelliferone, coumarin-5-methyl-4-glucoside, NMR, ESI-MS, Ecuador.
Resumen
Se caracterizó químicamente el extracto etanólico de Jungia rugosa Less, una popular especie andina perteneciente a la familia Asteraceae. Se eliminó las clorofilas al extracto mediante extracción en fase sólida, utilizando como fase sólida resina de Diaion Hp-20 y eluyendo con una mezcla de EtOH/H2O según un gradiente de polaridad decreciente. El extracto libre de clorofila se fraccionó repetidamente mediante cromatografía en columna abierta en fase normal y cromatografía en capa fina preparativa. Finalmente, se purificaron e identificaron dos metabolitos principales mediante la elucidación de la estructura. Se utilizaron espectroscopía de resonancia magnética nuclear (RMN) y espectrometría de masas de ionización por aspersión de electrones (ESI-MS). Los metabolitos identificados fueron las cumarinas: umbeliferona (1) y cumarina-5-metil-4α-glucósido (2). El compuesto 1 es conocido en la literatura por tener actividad antiinflamatoria, antihiperglucémica y antitumoral. El compuesto 2 no se ha descrito antes para este género botánico y sus efectos farmacológicos aún no se han investigado.
Palabras Clave: Jungia rugosa, umbeliferona, cumarina-5-metil-4-glucósido, RMN, ESI-MS, Ecuador
Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst
Positive effects of the polymeric support on the performance of supported chiral catalysts, in terms of activity, stability and selectivity–enantioselectivity, have been reported when the support is properly selected and optimized opening the way to the design of more efficient catalytic systems
MS 2053.7-0449: Confirmation of a bimodal mass distribution from strong gravitational lensing
We present the first strong lensing study of the mass distribution in the
cluster MS 2053-04 based on HST archive data. This massive, X-ray luminous
cluster has a redshift z=0.583, and it is composed of two structures that are
gravitationally bound to each other. The cluster has one multiply imaged system
constituted by a double gravitational arc.
We have performed a parametric strong lensing mass reconstruction using NFW
density profiles to model the cluster potential. We also included perturbations
from 23 galaxies, modeled like elliptical singular isothermal sphere, that are
approximately within 1'x1' around the cluster center. These galaxies were
constrained in both the geometric and dynamical parameters with observational
data. Our analysis predicts a third image which is slightly demagnified. We
found a candidate for this counter-image near the expected position and with
the same F702W-F814W colors as the gravitational arcs in the cluster. The
results from the strong lensing model shows the complex structure in this
cluster, the asymmetry and the elongation in the mass distribution, and are
consistent with previous spectrophotometric results that indicate that the
cluster has a bimodal mass distribution. Finally, the derived mass profile was
used to estimate the mass within the arcs and for comparison with X-ray
estimates.Comment: To be published in ApJ (accepted
Strong lensing, weak lensing, and dynamics in SL2S J02140-0535
International audienceWe combine strong lensing modeling and dynamical constraints in order to probe the mass of SL2S J02140-0535, a galaxy group at z = 0.44 from the Strong Lensing Legacy Survey (SL2S) which has uncovered a new population of group-scale strong lenses. The strong lensing analysis is based on multi-band HST/ACS observations which display strong lensing features that we have followed up spectroscopically with VLT/FORS2. To constrain the scale radius of an NFW mass profile, we propose a new method taking advantage of the large scale dynamical information provided by VLT/FORS2 and KECK/LRIS spectroscopy of group members. This work shows a potentially useful method for constraining large-scale properties inaccessible to strong lensing, such as the scale radius of the NFW profile
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