Discovery of a New Quadruple Lens HST 1411+5211

Gravitational lensing is an important tool for probing the mass distribution of galaxies. In this letter we report the discovery of a new quadruple lens HST 1411+5211 found in archived WFPC2 images of the galaxy cluster CL140933+5226. If the galaxy is a cluster member then its redshift is $z=0.46$. The images of the source appear unresolved in the WFC implying that the source is a quasar. We have modeled the lens as both a single galaxy and a galaxy plus a cluster. The latter model yields excellent fits to the image positions along with reasonable parameters for the galaxy and cluster making HST 1411+5211 a likely gravitational lens. Determination of the source redshift and confirmation of the lens redshift would allow us to put strong constraints on the mass distribution of the lensing galaxy.Comment: 11 pages including 1 postscript figure, aastex. Accepted to the ApJL. Also available from: http://www.astro.lsa.umich.edu:80/users/philf/www/papers/list.htm

Spectroscopy of moderately high-redshift RCS-1 clusters

We present spectroscopic observations of 11 moderately high-redshift (z~0.7- 1.0) clusters from the first Red-Sequence Cluster Survey (RCS-1). We find excellent agreement between the red-sequence estimated redshift and the spectroscopic redshift, with a scatter of 10% at z>0.7. At the high-redshift end (z>~0.9) of the sample, we find two of the systems selected are projections of pairs of comparably rich systems, with red-sequences too close to discriminate in (R-z') colour. In one of these systems, the two components are close enough to be physically associated. For a subsample of clusters with sufficient spectroscopic members, we examine the correlation between B_gcR (optical richness) and the dynamical mass inferred from the velocity dispersion. We find these measurements to be compatible, within the relatively large uncertainties, with the correlation established at lower redshift for the X-ray selected CNOC1 clusters and also for a lower redshift sample of RCS-1 clusters. Confirmation of this and calibration of the scatter in the relation will require larger samples of clusters at these and higher redshifts. [abridged]Comment: AJ accepted. 30 pages, 7 figures (figure 5 reduced quality

Squark Loop Correction to W^{+-} H^{-+} Associated Hadroproduction

We study the squark loop correction to W^{+-} H^{-+} associated hadroproduction via gluon-gluon fusion within the minimal supersymmetric extension of the standard model. We list full analytic results and quantitatively analyze the resulting shift in the cross section at the CERN Large Hadron Collider assuming a supergravity-inspired scenario.Comment: 13 pages (Latex), 5 figures (Postscript

Galaxy Clusters in the Line of Sight to Background Quasars: I. Survey Design and Incidence of MgII Absorbers at Cluster Redshifts

We describe the first optical survey of absorption systems associated with galaxy clusters at z= 0.3-0.9. We have cross-correlated SDSS DR3 quasars with high-redshift cluster/group candidates from the Red-Sequence Cluster Survey. We have found 442 quasar-cluster pairs for which the MgII doublet might be detected at a transverse (physical) distance d<2 Mpc from the cluster centers. To investigate the incidence (dN/dz) and equivalent-width distribution n(W) of MgII systems at cluster redshifts, two statistical samples were drawn out of these pairs: one made of high-resolution spectroscopic quasar observations (46 pairs), and one made of quasars used in MgII searches found in the literature (375 pairs). The results are: (1) the population of strong MgII systems (W_0>2.0 Ang.) near cluster redshifts shows a significant (>3 sigma) overabundance (up to a factor of 15) when compared with the 'field' population; (2) the overabundance is more evident at smaller distances (d<1 Mpc) than larger distances (d<2 Mpc) from the cluster center; and, (3) the population of weak MgII systems (W_0<0.3 Ang.) near cluster redshifts conform to the field statistics. Unlike in the field, this dichotomy makes n(W) in clusters appear flat and well fitted by a power-law in the entire W-range. A sub-sample of the most massive clusters yields a stronger and still significant signal. Since either the absorber number density or filling-factor/cross-section affects the absorber statistics, an interesting possibility is that we have detected the signature of truncated halos due to environmental effects. Thus, we argue that the excess of strong systems is due to a population of absorbers in an overdense galaxy environment, and the lack of weak systems to a different population, that got destroyed in the cluster environment. (Abridged)Comment: Accepted for publication in the Astrophysical Journa

Cosmic Evolution of a Sample of Infrared Luminous Galaxies

A sample of faint, southern-hemisphere 60 μm sources (f_(60) > 100mJy) detected as part of the IRAS Additional Observations has been used, in conjunction with CCD imaging, to produce a list of faint infrared galaxies. Redshifts of this sample of galaxies can be compared with model predictions for several evolutionary scenarios; the comparisons show an excess of galaxies at higher redshifts (z > 0.1) compared with the predictions of models which assume no evolution of the infrared-galaxy luminosity function

La identificación del uso de fuentes secundarias de materiales líticos asistida por SIG: el Arroyo Chasicó (Argentina) como caso de estudio

The aim of this paper is to present the methodology deployed in the Chasicó basin (southern Pampas, Argentina) in order to discuss the differential contribution of primary and secondary lithic sources in the spatial and technological organization of late Holocene hunter-gatherers societies. Such methodology is based on the comparative analysis of curves constructed with data obtained from virtual transects traced over continuous spatial models representing different properties of regional lithic landscapes. Those models were created by interpolation using a technique called Inverse Distance Weighted (IDW) from scattered information recovered at point locations (i.e. archaeological sites and localities; n = 12). Investigated raw materials were rhyolites and two varieties of quartzites, and the monitored variables were relative frequency (F%), relative weight (P%) and cortex index (IC). Our results suggest that both varieties of quartzites were mainly procured from secondary sources distributed along the basin and that rhyolites were mostly obtained from primary sources located at the headwaters.El objetivo de este trabajo es presentar la metodología implementada en la cuenca del Arroyo Chasicó (sur de la Región Pampeana Argentina), orientada a discutir el uso diferencial de fuentes de materias primas líticas primarias y secundarias en relación con la organización espacial y tecnológica en sociedades cazadoras-recolectoras del Holoceno tardío. La metodología se basa en el análisis comparativo de curvas construidas con datos procedentes de transectos virtuales, trazados sobre modelos espaciales continuos representando diferentes propiedades de los “paisajes líticos” del área de estudio. Tales modelos se generaron por interpolación mediante la técnica denominada Inverse Distance Weighted (IDW) a partir de información procedente de localizaciones puntuales (i.e. sitios y localidades arqueológicos; n = 12). Las materias primas investigadas fueron riolitas y dos variedades de cuarcita y las variables consideradas fueron frecuencia relativa y peso relativo, expresadas ambas en términos porcentuales (F% y P%, respectivamente) e índice de corteza (IC). Los resultados obtenidos indican que, para ambas variedades de cuarcitas, la explotación de fuentes secundarias —distribuidas a lo largo de la cuenca— fue mayor que la de las primarias, mientras que las riolitas fueron obtenidas, principalmente, de las fuentes primarias situadas en las cabeceras

The Red-Sequence Luminosity Function in Galaxy Clusters since z~1

We use a statistical sample of ~500 rich clusters taken from 72 square degrees of the Red-Sequence Cluster Survey (RCS-1) to study the evolution of ~30,000 red-sequence galaxies in clusters over the redshift range 0.35<z<0.95. We construct red-sequence luminosity functions (RSLFs) for a well-defined, homogeneously selected, richness limited sample. The RSLF at higher redshifts shows a deficit of faint red galaxies (to M_V=> -19.7) with their numbers increasing towards the present epoch. This is consistent with the `down-sizing` picture in which star-formation ended at earlier times for the most massive (luminous) galaxies and more recently for less massive (fainter) galaxies. We observe a richness dependence to the down-sizing effect in the sense that, at a given redshift, the drop-off of faint red galaxies is greater for poorer (less massive) clusters, suggesting that star-formation ended earlier for galaxies in more massive clusters. The decrease in faint red-sequence galaxies is accompanied by an increase in faint blue galaxies, implying that the process responsible for this evolution of faint galaxies is the termination of star-formation, possibly with little or no need for merging. At the bright end, we also see an increase in the number of blue galaxies with increasing redshift, suggesting that termination of star-formation in higher mass galaxies may also be an important formation mechanism for higher mass ellipticals. By comparing with a low-redshift Abell Cluster sample, we find that the down-sizing trend seen within RCS-1 has continued to the local universe.Comment: ApJ accepted. 11 pages, 5 figure

Spatially Resolved Outflows in a Seyfert Galaxy at z = 2.39

We present the first spatially resolved analysis of rest-frame optical and UV imaging and spectroscopy for a lensed galaxy at z = 2.39 hosting a Seyfert active galactic nucleus (AGN). Proximity to a natural guide star has enabled high signal-to-noise VLT SINFONI + adaptive optics observations of rest-frame optical diagnostic emission lines, which exhibit an underlying broad component with FWHM ~ 700 km/s in both the Balmer and forbidden lines. Measured line ratios place the outflow robustly in the region of the ionization diagnostic diagrams associated with AGN. This unique opportunity - combining gravitational lensing, AO guiding, redshift, and AGN activity - allows for a magnified view of two main tracers of the physical conditions and structure of the interstellar medium in a star-forming galaxy hosting a weak AGN at cosmic noon. By analyzing the spatial extent and morphology of the Ly-alpha and dust-corrected H-alpha emission, disentangling the effects of star formation and AGN ionization on each tracer, and comparing the AGN induced mass outflow rate to the host star formation rate, we find that the AGN does not significantly impact the star formation within its host galaxy.Comment: 16 pages, 5 figures, accepted for publication in Ap

Galaxy scale lenses in the RCS2: I. First Catalog of Candidate Strong Lenses

We present the first galaxy scale lens catalog from the second Red-Sequence Cluster Survey. The catalog contains 60 lensing system candidates comprised of Luminous Red Galaxy (LRG) lenses at 0.2 < z < 0.5 surrounded by blue arcs or apparent multiple images of background sources. The catalog is a valuable complement to previous galaxy-galaxy lens catalogs as it samples an intermediate lens redshift range and is composed of bright sources and lenses that allow easy follow-up for detailed analysis. Mass and mass-to-light ratio estimates reveal that the lens galaxies are massive (~5.5x10e11 M_sun/h) and rich in dark matter (~14 M_sun/L_sun,B*h). Even though a slight increasing trend in the mass-to-light ratio is observed from z=0.2 to z=0.5, current redshift and light profile measurements do not allow stringent constraints on the mass-to-light ratio evolution of LRGs.Comment: ApJ in press. Updated to match print versio