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Search Results: 1 - 10 of 37849 matches for " Marcelle Soares-Santos "
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Dark energy physics expectations at DES
Marcelle Soares-Santos
Physics , 2012, DOI: 10.1088/1742-6596/375/3/032006
Abstract: Giving rise to a new and exciting research field, observations of the last 13 years established the accelerated expansion of the Universe. This is a strong indication of new physics, either in the form of a new energy component of the Universe -- dark energy -- or of theories of gravity beyond general relativity. A powerful approach to this problem is the study of complementary cosmological probes in large optical galaxy surveys such as the Dark Energy Survey (DES). We present the expectations for dark energy physics based on the combination of four fundamental probes: galaxy clusters, weak lensing, large scale structure and supernovae. We show that DES data have constraining power to improve current measurements of the dark energy equation-of-state parameter by a factor of 3--5 and to distinguish between general relativity and modified gravity scenarios.
The SDSS Coadd: Cross-Correlation Weak Lensing and Tomography of Galaxy Clusters
Melanie Simet,Jeffrey M. Kubo,Scott Dodelson,James T. Annis,Jiangang Hao,David Johnston,Huan Lin,Ribamar R. R. Reis,Marcelle Soares-Santos,Hee-Jong Seo
Physics , 2011, DOI: 10.1088/0004-637X/748/2/128
Abstract: The shapes of distant galaxies are sheared by intervening galaxy clusters. We examine this effect in Stripe 82, a 275 square degree region observed multiple times in the Sloan Digital Sky Survey and coadded to achieve greater depth. We obtain a mass-richness calibration that is similar to other SDSS analyses, demonstrating that the coaddition process did not adversely affect the lensing signal. We also propose a new parameterization of the effect of tomography on the cluster lensing signal which does not require binning in redshift, and we show that using this parameterization we can detect tomography for stacked clusters at varying redshifts. Finally, due to the sensitivity of the tomographic detection to accurately marginalizing over the effect of the cluster mass, we show that tomography at low redshift (where dependence on exact cosmological models is weak) can be used to constrain mass profiles in clusters.
The SDSS Coadd: A Galaxy Photometric Redshift Catalog
Ribamar R. R. Reis,Marcelle Soares-Santos,James Annis,Scott Dodelson,Jiangang Hao,David Johnston,Jeffrey Kubo,Huan Lin,Hee-Jong Seo,Melanie Simet
Physics , 2011, DOI: 10.1088/0004-637X/747/1/59
Abstract: We present and describe a catalog of galaxy photometric redshifts (photo-z's) for the Sloan Digital Sky Survey (SDSS) Coadd Data. We use the Artificial Neural Network (ANN) technique to calculate photo-z's and the Nearest Neighbor Error (NNE) method to estimate photo-z errors for $\sim$ 13 million objects classified as galaxies in the coadd with $r < 24.5$. The photo-z and photo-z error estimators are trained and validated on a sample of $\sim 83,000$ galaxies that have SDSS photometry and spectroscopic redshifts measured by the SDSS Data Release 7 (DR7), the Canadian Network for Observational Cosmology Field Galaxy Survey (CNOC2), the Deep Extragalactic Evolutionary Probe Data Release 3(DEEP2 DR3), the VIsible imaging Multi-Object Spectrograph - Very Large Telescope Deep Survey (VVDS) and the WiggleZ Dark Energy Survey. For the best ANN methods we have tried, we find that 68% of the galaxies in the validation set have a photo-z error smaller than $\sigma_{68} =0.031$. After presenting our results and quality tests, we provide a short guide for users accessing the public data.
The SDSS Coadd: Cosmic Shear Measurement
Huan Lin,Scott Dodelson,Hee-Jong Seo,Marcelle Soares-Santos,James Annis,Jiangang Hao,David Johnston,Jeffrey M. Kubo,Ribamar R. R. Reis,Melanie Simet
Physics , 2011, DOI: 10.1088/0004-637X/761/1/15
Abstract: Stripe 82 in the Sloan Digital Sky Survey was observed multiple times, allowing deeper images to be constructed by coadding the data. Here we analyze the ellipticities of background galaxies in this 275 square degree region, searching for evidence of distortions due to cosmic shear. The E-mode is detected in both real and Fourier space with $>5$-$\sigma$ significance on degree scales, while the B-mode is consistent with zero as expected. The amplitude of the signal constrains the combination of the matter density $\Omega_m$ and fluctuation amplitude $\sigma_8$ to be $\Omega_m^{0.7}\sigma_8 = 0.252^{+0.032}_{-0.052}$.
The Sloan Nearby Cluster Weak Lensing Survey
Jeffrey M. Kubo,James Annis,Frances Mei Hardin,Donna Kubik,Kelsey Lawhorn,Huan Lin,Liana Nicklaus,Dylan Nelson,Ribamar R. R. Reis,Hee-Jong Seo,Marcelle Soares-Santos,Albert Stebbins,Tony Yunker
Physics , 2009, DOI: 10.1088/0004-637X/702/2/L110
Abstract: We describe and present initial results of a weak lensing survey of nearby ($\rm{z}\lesssim0.1$) galaxy clusters in the Sloan Digital Sky Survey (SDSS). In this first study, galaxy clusters are selected from the SDSS spectroscopic galaxy cluster catalogs of \citet{miller05} and \citet{berlind06}. We report a total of seven individual low redshift cluster weak lensing measurements which include: A2048, A1767, A2244, A1066, A2199, and two clusters specifically identified with the C4 algorithm. Our program of weak lensing of nearby galaxy clusters in the SDSS will eventually reach $\sim 200$ clusters, making it the largest weak lensing survey of individual galaxy clusters to date.
The Sloan Bright Arcs Survey : Discovery of Seven New Strongly Lensed Galaxies from z=0.66-2.94
Jeffrey M. Kubo,Sahar S. Allam,Emily Drabek,Huan Lin,Douglas Tucker,Elizabeth J. Buckley-Geer,H. Thomas Diehl,Marcelle Soares-Santos,Jiangang Hao,Matthew Wiesner,Anderson West,Donna Kubik,James Annis,Joshua A. Frieman
Physics , 2010, DOI: 10.1088/2041-8205/724/2/L137
Abstract: We report the discovery of seven new, very bright gravitational lens systems from our ongoing gravitational lens search, the Sloan Bright Arcs Survey (SBAS). Two of the systems are confirmed to have high source redshifts z=2.19 and z=2.94. Three other systems lie at intermediate redshift with z=1.33,1.82,1.93 and two systems are at low redshift z=0.66,0.86. The lensed source galaxies in all of these systems are bright, with i-band magnitudes ranging from 19.73-22.06. We present the spectrum of each of the source galaxies in these systems along with estimates of the Einstein radius for each system. The foreground lens in most systems is identified by a red sequence based cluster finder as a galaxy group; one system is identified as a moderately rich cluster. In total the SBAS has now discovered 19 strong lens systems in the SDSS imaging data, 8 of which are among the highest surface brightness z\simeq2-3 galaxies known.
The Voronoi Tessellation cluster finder in 2+1 dimensions
Marcelle Soares-Santos,Reinaldo R. de Carvalho,James Annis,Roy R. Gal,Francesco La Barbera,Paulo A. A. Lopes,Risa H. Wechsler,Michael T. Busha,Brian F. Gerke
Physics , 2010, DOI: 10.1088/0004-637X/727/1/45
Abstract: We present a detailed description of the Voronoi Tessellation (VT) cluster finder algorithm in 2+1 dimensions, which improves on past implementations of this technique. The need for cluster finder algorithms able to produce reliable cluster catalogs up to redshift 1 or beyond and down to $10^{13.5}$ solar masses is paramount especially in light of upcoming surveys aiming at cosmological constraints from galaxy cluster number counts. We build the VT in photometric redshift shells and use the two-point correlation function of the galaxies in the field to both determine the density threshold for detection of cluster candidates and to establish their significance. This allows us to detect clusters in a self consistent way without any assumptions about their astrophysical properties. We apply the VT to mock catalogs which extend to redshift 1.4 reproducing the $\Lambda$CDM cosmology and the clustering properties observed in the SDSS data. An objective estimate of the cluster selection function in terms of the completeness and purity as a function of mass and redshift is as important as having a reliable cluster finder. We measure these quantities by matching the VT cluster catalog with the mock truth table. We show that the VT can produce a cluster catalog with completeness and purity $>80%$ for the redshift range up to $\sim 1$ and mass range down to $\sim 10^{13.5}$ solar masses.
Bats from the Atlantic rainforest of southern Bahia, Brazil
Faria, Deborah;Soares-Santos, Binael;Sampaio, Erica;
Biota Neotropica , 2006, DOI: 10.1590/S1676-06032006000200022
Abstract: data collected during 16 years of bat surveys (1986 to 2002) in southern bahia, brazil, is presented here. bats were surveyed in 14 municipalities, in habitats that included residences, caves, forests and agricultural areas, resulting in a total of 6576 captures of 60 species from the bat families emballonuridae (5 sp), noctilionidae (1 sp), phyllostomidae (46 sp), thyropteridae (1 sp), natalidae (1 sp), molossidae (3 sp) and vespertilionidae (2 sp). these data include 29 species not previously documented for the state of bahia. we also report the first record of vampyrodes caraccioli for this biome, extending its distribution over 3.000 km eastwards. the present data significantly increase the knowledge of the bat fauna of bahia, providing an updated list of 78 documented species, belonging to 50 different genera and eight families.
On the evolution of primordial gravitational waves: a semi-analytic detailed approach
M. Soares-Santos,E. M. de Gouveia Dal Pino
Physics , 2006,
Abstract: A cosmological gravitational wave background resulting from space-time quantum perturbations at energy scales of $\sim 10^{15}$GeV is expected as a consequence of the general relativity theory in the context of the standard cosmological model. Initial conditions %for the problem are determined during the inflationary (de Sitter) era, at $z \gtrsim 10^{25} $. A semi-analytic method was developed to evolve the system up to the present with no need of simplifying approximations as the thin-horizon (super-adiabatic) or the instantaneous transitions between the successive phases of domain of the different cosmic fluids. The accuracy of such assumptions, broadly employed in the literature, is put in check. Since the physical nature of the fluid (known as dark energy) leading to the accelerated expansion observed in the recent Universe is still uncertain, four categories of models were analyzed: cosmological constant, X-fluid (phantom or not), generalized Chaplygin gas and (a parametric form of) quintessence. The results are conclusive with respect to the insensitivity of gravitational waves to dark energy, due to the recentness of its phase of domain ($z \sim 1 $). The empirical counterparts of the gravitational wave forecasts are still nonexistent for the noise levels and operational frequencies of the experiments already built are inadequate to detect those relics. Perspectives are more promising for space detectors (planned to be sensitive to amplitudes of $\sim 10^{-23}$ at $10^{-3}-1$Hz). The cosmic microwave background is also discussed as an alternative of indirect detection and the energy density scale of inflation is constrained to be smaller than $10^{-10}$ in the analysis here presented.
The SDSS Coadd: 275 deg^2 of Deep SDSS Imaging on Stripe 82
James Annis,Marcelle Soares-Santos,Michael A. Strauss,Andrew C. Becker,Scott Dodelson,Xiaohui Fan,James E. Gunn,Jiangang Hao,Zeljko Ivezic,Sebastian Jester,Linhua Jiang,David E. Johnston,Jeffrey M. Kubo,Hubert Lampeitl,Huan Lin,Robert H. Lupton,Gajus Miknaitis,Hee-Jong Seo,Melanie Simet,Brian Yanny
Physics , 2011, DOI: 10.1088/0004-637X/794/2/120
Abstract: We present details of the construction and characterization of the coaddition of the Sloan Digital Sky Survey Stripe 82 \ugriz\ imaging data. This survey consists of 275 deg$^2$ of repeated scanning by the SDSS camera of $2.5\arcdeg$ of $\delta$ over $-50\arcdeg \le \alpha \le 60\arcdeg$ centered on the Celestial Equator. Each piece of sky has $\sim 20$ runs contributing and thus reaches $\sim2$ magnitudes fainter than the SDSS single pass data, i.e. to $r\sim 23.5$ for galaxies. We discuss the image processing of the coaddition, the modeling of the PSF, the calibration, and the production of standard SDSS catalogs. The data have $r$-band median seeing of 1.1\arcsec, and are calibrated to $\le 1%$. Star color-color, number counts, and psf size vs modelled size plots show the modelling of the PSF is good enough for precision 5-band photometry. Structure in the psf-model vs magnitude plot show minor psf mis-modelling that leads to a region where stars are being mis-classified as galaxies, and this is verified using VVDS spectroscopy. As this is a wide area deep survey there are a variety of uses for the data, including galactic structure, photometric redshift computation, cluster finding and cross wavelength measurements, weak lensing cluster mass calibrations, and cosmic shear measurements.
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