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 $z$ = 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 $z$ = 1.7 $\pm$ 0.1 produces three images, while the other at $z$ = 1.023 $\pm$ 0.001 has only a single image. Our unimodal NFW mass model reproduces these images very well. It is characterized by a concentration parameter $c_{200}$ = 6.0 $\pm$ 0.6, which is slightly greater than the value expected from $\Lambda$CDM simulations for a mass of M$_{200}$ $\approx$ 1 $\times$ 10$^{14}$ 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&

High dispersion spectroscopy of two A supergiant systems in the Small Magellanic Cloud with novel properties

We present the results of a spectroscopic investigation of two novel variable bright blue stars in the SMC, OGLE004336.91-732637.7 (SMC-SC3) and the periodically occulted star OGLE004633.76-731204.3 (SMC-SC4), whose photometric properties were reported by Mennickent et al. (2010). High-resolution spectra in the optical and far-UV show that both objects are actually A + B type binaries. Three spectra of SMC-SC4 show radial velocity variations, consistent with the photometric period of 184.26 days found in Mennickent et al. 2010. The optical spectra of the metallic lines in both systems show combined absorption and emission components that imply that they are formed in a flattened envelope. A comparison of the radial velocity variations in SMC-SC4 and the separation of the V and R emission components in the Halpha emission profile indicate that this envelope, and probably also the envelope around SMC-SC3, is a circumbinary disk with a characteristic orbital radius some three times the radius of the binary system. The optical spectra of SMC-SC3 and SMC-SC4 show, respectively, HeI emission lines and discrete Blue Absorption Components (BACs) in metallic lines. The high excitations of the HeI lines in the SMC-SC3 spectrum and the complicated variations of FeII emission and absorption components with orbital phase in the spectrum of SMC-SC4 suggests that shocks occur between the winds and various static regions of the stars' co-rotating binary-disk complexes. We suggest that BACs arise from wind shocks from the A star impacting the circumbinary disk and a stream of former wind-efflux from the B star accreting onto the A star. We dub these objects prototype of a small group of Magellanic Cloud wind-interacting A + B binaries.Comment: To be published in MNRA

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

School quality, safe schools: an emperical analysis

While the vast majority of US public schools are safe, problems exist that not only threaten the teaching and learning environment, but cause substantive problems for educators. Sensing that certain troubling student behaviors can lead to greater problems, schools have implemented many safe school programs and strategies. Unfortunately, these approaches are viewed as "add-ons" by the education community; that is, additional activities and work for them. What is needed is a framework where safe school programs and strategies are fully integrated into the schooling process. Such a framework exists, and the purpose of our paper has been to integrate the safe schools literature with the quality schools literature in developing such a framework. After reviewing the school quality and school safety literature we extracted main concepts from both bodies of research, and led to an overriding proposition. The proposition suggests that safe school activities can be successful if they are part of the larger task of developing and sustaining quality schools. An analysis of school quality and safety data collected by the NEA tentatively confirms our main proposition. We found that school quality is significantly related to school safety. Additional findings suggest that safety varies across schools, middle schools have more problems than either elementary or high schools, and that the effect of school quality on safety does not depend on grade level. Taken as a whole, the effect of school quality on school safety appears to be very robus

The Decline of the Non-Hispanic White Population in the United States of America

Objectives: The question of a declining non-Hispanic white (NHW) population has sparked debate in the United States. In examining this question, three bodies of research have emerged. One group reports that the decline is real, a second argues that it is an illusion, and the third provides evidence that the decline is concentrated within socio-economic segments of the NHW population. We use the third groups’ insight as the starting point for our research objective. Methods: In conjunction with data from Census Bureau sources, we use a series of Regression Models in this inquiry. Results: Our results show that the decline of the NHW population is real and related to factors embedded in the institutional anomie theory (IAT) framework. Conclusions: We conclude that the IAT framework is a suitable approach for examining the question of NHW population decline. However, we suggest that future research consider refining our approach by: (1) using sub-state areas as the units of analyses; (2) examining changes in the NHW population relative to lagged changes in the IAT framework at both the state and sub-state levels; (3) placing our framework into an “algorithmic modeling approach” that employs machine learning; and (4) developing anomie predictors

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

Phenological cycle and floral development of Chloraea crispa (Orchidaceae)

Vogel, H (Vogel, Hermine).Univ Talca, Fac Ciencias Agr, Talca, ChileU. Steinfort, M.A. Cisternas, R. Garcia, H. Vogel, and G. Verdugo. 2012. Phenological cycle and floral development of Chloraea crispa (Orchidaceae). Cien. Inv. Agr. 39(2): 377-385. Chloraea crispa Lindl. is a terrestrial orchid endemic to Chile that has potential to be a novel alternative for the cut flower industry. The objectives of this study were to describe the phenological cycle and floral bud development of C. crispa to determine the timing of initiation and differentiation of the spike. During the summer, plants are dormant. The renewal buds are located at the top of the rhizome, next to the buds from which the shoot of the previous season originated. From the end of summer until the end of winter, the plant is in vegetative growth. From June onward, the flower stalk starts to emerge, and flowering and leaf senescence occur during the spring until the beginning of summer. The renewal buds started forming leaf primordia during or after the flowering of the above-ground annual stems and the senescence of the plant. Between December and January, the apical meristem changes to the reproductive stage, and from March, the first flower primordial could be observed. C. crispa shows similarity with other geophytes in which florogenesis and the development of new organs occurs within the renewal buds during or after the summer dormancy period

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