7 results on '"Grillo, Claudio"'
Search Results
2. HUBBLE SPACE TELESCOPE COMBINED STRONG AND WEAK LENSING ANALYSIS OF THE CLASH SAMPLE: MASS AND MAGNIFICATION MODELS AND SYSTEMATIC UNCERTAINTIES.
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Zitrin, Adi, Fabris, Agnese, Merten, Julian, Melchior, Peter, Meneghetti, Massimo, Koekemoer, Anton, Coe, Dan, Maturi, Matteo, Bartelmann, Matthias, Postman, Marc, Umetsu, Keiichi, Seidel, Gregor, Sendra, Irene, Broadhurst, Tom, Balestra, Italo, Biviano, Andrea, Grillo, Claudio, Mercurio, Amata, Nonino, Mario, and Rosati, Piero
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GALAXY clusters ,GRAVITATIONAL lenses ,DARK matter ,REDSHIFT - Abstract
We present results from a comprehensive lensing analysis in Hubble Space Telescope (HST) data of the complete Cluster Lensing And Supernova survey with Hubble cluster sample. We identify previously undiscovered multiple images, allowing improved or first constraints on the cluster inner mass distributions and profiles. We combine these strong lensing constraints with weak lensing shape measurements within the HST field of view (FOV) to jointly constrain the mass distributions. The analysis is performed in two different common parameterizations (one adopts light-traces-mass for both galaxies and dark matter while the other adopts an analytical, elliptical Navarro-Frenk-White form for the dark matter) to provide a better assessment of the underlying systematics—which is most important for deep, cluster-lensing surveys, especially when studying magnified high-redshift objects. We find that the typical (median), relative systematic differences throughout the central FOV are ∼40% in the (dimensionless) mass density, κ, and ∼20% in the magnification, μ. We show maps of these differences for each cluster, as well as the mass distributions, critical curves, and two-dimensional (2D)-integrated mass profiles. For the Einstein radii (z
s = 2) we find that all typically agree within 10% between the two models, and Einstein masses agree, typically, within ∼15%. At larger radii, the total projected, 2D-integrated mass profiles of the two models, within r ∼ 2′, differ by ∼30%. Stacking the surface-density profiles of the sample from the two methods together, we obtain an average slope of dlog (Σ)/dlog (r) ∼ –0.64 ± 0.1, in the radial range [5350] kpc. Last, we also characterize the behavior of the average magnification, surface density, and shear differences between the two models as a function of both the radius from the center and the best-fit values of these quantities. All mass models and magnification maps are made publicly available for the community. [ABSTRACT FROM AUTHOR]- Published
- 2015
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3. CLASH: WEAK-LENSING SHEAR-AND-MAGNIFICATION ANALYSIS OF 20 GALAXY CLUSTERS.
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Umetsu, Keiichi, Medezinski, Elinor, Nonino, Mario, Merten, Julian, Postman, Marc, Meneghetti, Massimo, Donahue, Megan, Czakon, Nicole, Molino, Alberto, Seitz, Stella, Gruen, Daniel, Lemze, Doron, Balestra, Italo, Benítez, Narciso, Biviano, Andrea, Broadhurst, Tom, Ford, Holland, Grillo, Claudio, Koekemoer, Anton, and Melchior, Peter
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DARK matter ,OPEN clusters of stars ,METAPHYSICAL cosmology ,STAR clusters ,GRAVITATIONAL lenses - Abstract
We present a joint shear-and-magnification weak-lensing analysis of a sample of 16 X-ray-regular and 4 high-magnification galaxy clusters at 0.19 ≲ z ≲ 0.69 selected from the Cluster Lensing And Supernova survey with Hubble (CLASH). Our analysis uses wide-field multi-color imaging, taken primarily with Suprime-Cam on the Subaru Telescope. From a stacked-shear-only analysis of the X-ray-selected subsample, we detect the ensemble-averaged lensing signal with a total signal-to-noise ratio of ≃ 25 in the radial range of 200-3500 kpc h
–1 , providing integrated constraints on the halo profile shape and concentration-mass relation. The stacked tangential-shear signal is well described by a family of standard density profiles predicted for dark-matter-dominated halos in gravitational equilibrium, namely, the Navarro-Frenk-White (NFW), truncated variants of NFW, and Einasto models. For the NFW model, we measure a mean concentration of at an effective halo mass of . We show that this is in excellent agreement with Λ cold dark matter (ΛCDM) predictions when the CLASH X-ray selection function and projection effects are taken into account. The best-fit Einasto shape parameter is , which is consistent with the NFW-equivalent Einasto parameter of ∼0.18. We reconstruct projected mass density profiles of all CLASH clusters from a joint likelihood analysis of shear-and-magnification data and measure cluster masses at several characteristic radii assuming an NFW density profile. We also derive an ensemble-averaged total projected mass profile of the X-ray-selected subsample by stacking their individual mass profiles. The stacked total mass profile, constrained by the shear+magnification data, is shown to be consistent with our shear-based halo-model predictions, including the effects of surrounding large-scale structure as a two-halo term, establishing further consistency in the context of the ΛCDM model. [ABSTRACT FROM AUTHOR]- Published
- 2014
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4. CLASH-X: A COMPARISON OF LENSING AND X-RAY TECHNIQUES FOR MEASURING THE MASS PROFILES OF GALAXY CLUSTERS.
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Donahue, Megan, Voit, G. Mark, Mahdavi, Andisheh, Umetsu, Keiichi, Ettori, Stefano, Merten, Julian, Postman, Marc, Hoffer, Aaron, Baldi, Alessandro, Coe, Dan, Czakon, Nicole, Bartelmann, Mattias, Benitez, Narciso, Bouwens, Rychard, Bradley, Larry, Broadhurst, Tom, Ford, Holland, Gastaldello, Fabio, Grillo, Claudio, and Infante, Leopoldo
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GALAXY clusters ,X-ray spectra ,DARK matter ,GRAVITATIONAL lenses - Abstract
We present profiles of temperature, gas mass, and hydrostatic mass estimated from new and archival X-ray observations of CLASH clusters. We compare measurements derived from XMM and Chandra observations with one another and compare both to gravitational lensing mass profiles derived with CLASH Hubble Space Telescope and Subaru Telescope lensing data. Radial profiles of Chandra and XMM measurements of electron density and enclosed gas mass are nearly identical, indicating that differences in hydrostatic masses inferred from X-ray observations arise from differences in gas-temperature measurements. Encouragingly, gas temperatures measured in clusters by XMM and Chandra are consistent with one another at ∼100-200 kpc radii, but XMM temperatures systematically decline relative to Chandra temperatures at larger radii. The angular dependence of the discrepancy suggests that additional investigation on systematics such as the XMM point-spread function correction, vignetting, and off-axis responses is yet required. We present the CLASH-X mass-profile comparisons in the form of cosmology-independent and redshift-independent circular-velocity profiles. We argue that comparisons of circular-velocity profiles are the most robust way to assess mass bias. Ratios of Chandra hydrostatic equilibrium (HSE) mass profiles to CLASH lensing profiles show no obvious radial dependence in the 0.3-0.8 Mpc range. However, the mean mass biases inferred from the weak-lensing (WL) and SaWLens data are different. As an example, the weighted-mean value at 0.5 Mpc is 〈 b〉 = 0.12 for the WL comparison and 〈 b〉 = –0.11 for the SaWLens comparison. The ratios of XMM HSE mass profiles to CLASH lensing profiles show a pronounced radial dependence in the 0.3-1.0 Mpc range, with a weighted mean mass bias value rising to 〈 b〉 ≳ 0.3 at ∼1 Mpc for the WL comparison and 〈 b〉 ≈ 0.25 for the SaWLens comparison. The enclosed gas mass profiles from both Chandra and XMM rise to a value ≈1/8 times the total-mass profiles inferred from lensing at ≈0.5 Mpc and remain constant outside of that radius, suggesting that M
gas × 8 profiles may be an excellent proxy for total-mass profiles at ≳ 0.5 Mpc in massive galaxy clusters. [ABSTRACT FROM AUTHOR]- Published
- 2014
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5. CLASH: MASS DISTRIBUTION IN AND AROUND MACS J1206.2-0847 FROM A FULL CLUSTER LENSING ANALYSIS.
- Author
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Umetsu, Keiichi, Medezinski, Elinor, Nonino, Mario, Merten, Julian, Zitrin, Adi, Molino, Alberto, Grillo, Claudio, Carrasco, Mauricio, Donahue, Megan, Mahdavi, Andisheh, Coe, Dan, Postman, Marc, Koekemoer, Anton, Czakon, Nicole, Sayers, Jack, Mroczkowski, Tony, Golwala, Sunil, Koch, Patrick M., Lin, Kai-Yang, and Molnar, Sandor M.
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GALAXY clusters ,GRAVITATIONAL lenses ,METAPHYSICAL cosmology ,DARK matter - Abstract
We derive an accurate mass distribution of the galaxy cluster MACS J1206.2-0847 (z = 0.439) from a combined weak-lensing distortion, magnification, and strong-lensing analysis of wide-field Subaru BVR
c Ic z′ imaging and our recent 16-band Hubble Space Telescope observations taken as part of the Cluster Lensing And Supernova survey with Hubble program. We find good agreement in the regions of overlap between several weak- and strong-lensing mass reconstructions using a wide variety of modeling methods, ensuring consistency. The Subaru data reveal the presence of a surrounding large-scale structure with the major axis running approximately northwest-southeast (NW-SE), aligned with the cluster and its brightest galaxy shapes, showing elongation with a ∼2: 1 axis ratio in the plane of the sky. Our full-lensing mass profile exhibits a shallow profile slope dln Σ/dln R ∼ –1 at cluster outskirts (R ≳ 1 Mpc h–1 ), whereas the mass distribution excluding the NW-SE excess regions steepens farther out, well described by the Navarro-Frenk-White form. Assuming a spherical halo, we obtain a virial mass Mvir = (1.1 ± 0.2 ± 0.1) × 1015 M☼ h–1 and a halo concentration cvir = 6.9 ± 1.0 ± 1.2 (cvir ∼ 5.7 when the central 50 kpc h–1 is excluded), which falls in the range 4 ≲ 〈 c〉 ≲ 7 of average c(M, z) predictions for relaxed clusters from recent Λ cold dark matter simulations. Our full-lensing results are found to be in agreement with X-ray mass measurements where the data overlap, and when combined with Chandra gas mass measurements, they yield a cumulative gas mass fraction of 13.7+4.5 – 3.0 % at 0.7 Mpc h–1 (≈ 1.7 r2500 ), a typical value observed for high-mass clusters. [ABSTRACT FROM AUTHOR]- Published
- 2012
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6. An excess of small-scale gravitational lenses observed in galaxy clusters.
- Author
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Meneghetti, Massimo, Davoli, Guido, Bergamini, Pietro, Rosati, Piero, Natarajan, Priyamvada, Giocoli, Carlo, Caminha, Gabriel B., Metcalf, R. Benton, Rasia, Elena, Borgani, Stefano, Calura, Francesco, Grillo, Claudio, Mercurio, Amata, and Vanzella, Eros
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GRAVITATIONAL lenses , *GALAXY clusters , *DARK matter , *METAPHYSICAL cosmology , *STELLAR magnitudes - Abstract
Cold dark matter (CDM) constitutes most of the matter in the Universe. The interplay between dark and luminous matter in dense cosmic environments, such as galaxy clusters, is studied theoretically using cosmological simulations. Observations of gravitational lensing are used to characterize the properties of substructures—the small-scale distribution of dark matter—in clusters. We derive a metric, the probability of strong lensing events produced by dark-matter substructure, and compute it for 11 galaxy clusters. The observed cluster substructures are more efficient lenses than predicted by CDM simulations, by more than an order of magnitude. We suggest that systematic issues with simulations or incorrect assumptions about the properties of dark matter could explain our results. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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7. The probability of galaxy-galaxy strong lensing events in hydrodynamical simulations of galaxy clusters
- Author
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Massimo Meneghetti, Antonio Ragagnin, Stefano Borgani, Francesco Calura, Giulia Despali, Carlo Giocoli, Gian Luigi Granato, Claudio Grillo, Lauro Moscardini, Elena Rasia, Piero Rosati, Giuseppe Angora, Luigi Bassini, Pietro Bergamini, Gabriel B. Caminha, Giovanni Granata, Amata Mercurio, Robert Benton Metcalf, Priyamvada Natarajan, Mario Nonino, Giada Venusta Pignataro, Cinthia Ragone-Figueroa, Eros Vanzella, Ana Acebron, Klaus Dolag, Giuseppe Murante, Giuliano Taffoni, Luca Tornatore, Luca Tortorelli, Milena Valentini, Meneghetti, Massimo, Ragagnin, Antonio, Borgani, Stefano, Calura, Francesco, Despali, Giulia, Giocoli, Carlo, Granato, GIAN LUIGI, Grillo, Claudio, Moscardini, Lauro, Rasia, Elena, Rosati, Piero, Angora, Giuseppe, Bassini, Luigi, Bergamini, Pietro, Caminha, Gabriel B., Granata, Giovanni, Mercurio, Amata, Benton Metcalf, Robert, Natarajan, Priyamvada, Nonino, Mario, Venusta Pignataro, Giada, Cinthia, Ragone-Figueroa, Vanzella, Ero, Acebron, Ana, Dolag, Klau, Murante, Giuseppe, Taffoni, Giuliano, Tornatore, Luca, Tortorelli, Luca, and Valentini, Milena
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Cosmology and Nongalactic Astrophysic ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Astrophysics of Galaxies ,galaxie ,FOS: Physical sciences ,Astronomy and Astrophysics ,dark matter ,galaxies ,clusters general ,gravitational lensing strong ,Astrophysics ,Cosmology and Nongalactic Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysic ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Meneghetti et al. (2020) recently reported an excess of galaxy-galaxy strong lensing (GGSL) in galaxy clusters compared to expectations from the LCDM cosmological model. Theoretical estimates of the GGSL probability are based on the analysis of numerical hydrodynamical simulations in the LCDM cosmology. We quantify the impact of the numerical resolution and AGN feedback scheme adopted in cosmological simulations on the predicted GGSL probability and determine if varying these simulation properties can alleviate the gap with observations. We repeat the analysis of Meneghetti et al. (2020) on cluster-size halos simulated with different mass and force resolutions and implementing several independent AGN feedback schemes. We find that improving the mass resolution by a factor of ten and twenty-five, while using the same galaxy formation model that includes AGN feedback, does not affect the GGSL probability. We find similar results regarding the choice of gravitational softening. On the contrary, adopting an AGN feedback scheme that is less efficient at suppressing gas cooling and star formation leads to an increase in the GGSL probability by a factor between three and six. However, we notice that such simulations form overly massive subhalos whose contribution to the lensing cross-section would be significant while their Einstein radii are too large to be consistent with the observations. The primary contributors to the observed GGSL cross-sections are subhalos with smaller masses, that are compact enough to become critical for lensing. The population with these required characteristics appears to be absent in simulations., Comment: 13 pages, 11 figures. Submitted for publication on Astronomy and Astrophysics
- Published
- 2022
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