The Experts below are selected from a list of 45099 Experts worldwide ranked by ideXlab platform
Ping Li - One of the best experts on this subject based on the ideXlab platform.
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recovery of coherent data via low rank dictionary pursuit
Neural Information Processing Systems, 2014Co-Authors: Ping LiAbstract:The recently established RPCA [4] method provides a convenient way to restore low-rank matrices from grossly corrupted observations. While elegant in theory and powerful in reality, RPCA is not an ultimate solution to the low-rank matrix recovery problem. Indeed, its performance may not be perfect even when data are strictly low-rank. This is because RPCA ignores Clustering structures of the data which are ubiquitous in applications. As the number of Cluster grows, the coherence of data keeps increasing, and accordingly, the recovery performance of RPCA degrades. We show that the challenges raised by coherent data (i.e., data with high coherence) could be alleviated by Low-Rank Representation (LRR) [13], provided that the dictionary in LRR is configured appropriately. More precisely, we mathematically prove that if the dictionary itself is low-rank then LRR is immune to the coherence parameter which increases with the Underlying Cluster number. This provides an elementary principle for dealing with coherent data and naturally leads to a practical algorithm for obtaining proper dictionaries in unsupervised environments. Experiments on randomly generated matrices and real motion sequences verify our claims. See the full paper at arXiv:1404.4032.
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recovery of coherent data via low rank dictionary pursuit
arXiv: Methodology, 2014Co-Authors: Ping LiAbstract:The recently established RPCA method provides us a convenient way to restore low-rank matrices from grossly corrupted observations. While elegant in theory and powerful in reality, RPCA may be not an ultimate solution to the low-rank matrix recovery problem. Indeed, its performance may not be perfect even when data are strictly low-rank. This is because conventional RPCA ignores the Clustering structures of the data which are ubiquitous in modern applications. As the number of Cluster grows, the coherence of data keeps increasing, and accordingly, the recovery performance of RPCA degrades. We show that the challenges raised by coherent data (i.e., the data with high coherence) could be alleviated by Low-Rank Representation (LRR), provided that the dictionary in LRR is configured appropriately. More precisely, we mathematically prove that if the dictionary itself is low-rank then LRR is immune to the coherence parameter which increases with the Underlying Cluster number. This provides an elementary principle for dealing with coherent data. Subsequently, we devise a practical algorithm to obtain proper dictionaries in unsupervised environments. Our extensive experiments on randomly generated matrices verify our claims.
Lorenzo Lovisari - One of the best experts on this subject based on the ideXlab platform.
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the most massive galaxy Clusters m2c across cosmic time link between radial total mass distribution and dynamical state
Astronomy and Astrophysics, 2019Co-Authors: I Bartalucci, M Arnaud, G W Pratt, J Democles, Lorenzo LovisariAbstract:We study the dynamical state and the integrated total mass profiles of 75 massive (M500 > 5 × 1014 M⊙) Sunyaev–Zeldovich(SZ)-selected Clusters at 0.08 0.9. Using XMM-Newton imaging observations, we characterise the dynamical state with the centroid shift ⟨w⟩, the concentration CSB, and their combination, M, which simultaneously probes the core and the large-scale gas morphology. Using spatially resolved spectroscopy and assuming hydrostatic equilibrium, we derive the total integrated mass profiles. The mass profile shape is quantified by the sparsity, that is the ratio of M500 to M2500, the masses at density contrasts of 500 and 2500, respectively. We study the correlations between the various parameters and their dependence on redshift. We confirm that SZ-selected samples, thought to most accurately reflect the Underlying Cluster population, are dominated by disturbed and non-cool core objects at all redshifts. There is no significant evolution or mass dependence of either the cool core fraction or the centroid shift parameter. The M parameter evolves slightly with z, having a correlation coefficient of ρ = −0.2 ± 0.1 and a null hypothesis p-value of 0.01. In the high-mass regime considered here, the sparsity evolves minimally with redshift, increasing by 10% between z 0.55, an effect that is significant at less than 2σ. In contrast, the dependence of the sparsity on dynamical state is much stronger, increasing by a factor of ∼60% from the one third most relaxed to the one third most disturbed objects, an effect that is significant at more than 3σ. This is the first observational evidence that the shape of the integrated total mass profile in massive Clusters is principally governed by the dynamical state and is only mildly dependent on redshift. We discuss the consequences for the comparison between observations and theoretical predictions.
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the most massive galaxy Clusters m2c across cosmic time link between radial total mass distribution and dynamical state
arXiv: Cosmology and Nongalactic Astrophysics, 2019Co-Authors: I Bartalucci, M Arnaud, G W Pratt, J Democles, Lorenzo LovisariAbstract:We study the dynamical state and the integrated total mass profiles of 75 massive (M500 > 5 e+14 M_sun) SZ-selected Clusters at 0.08 0.9. Using XMM imaging observations, we characterise the dynamical state with the centroid shift, the concentration, and their combination, M, which simultaneously probes the core and the large scale gas morphology. Using spatially-resolved spectroscopy and assuming hydrostatic equilibrium, we derive the total integrated mass profiles. The mass profile shape is quantified by the sparsity, the ratio of M500 to M2500, the masses at density contrast 500 and 2500, respectively. We study the correlations between the various parameters and their dependence on redshift. We confirm that SZ-selected samples, thought to reflect most closely the Underlying Cluster population, are dominated by disturbed and non-cool core objects at all z. There is no significant evolution or mass dependence of either the cool core fraction or the centroid shift parameter. The M parameter evolves slightly with z, having a correlation coefficient of rho= -0.2 $\pm$ 0.1 and a null hypothesis p-value of 0.01. In the high mass regime considered here, the sparsity evolves minimally with redshift, increasing by 10% between z 0.55, an effect significant at less than 2 sigma. In contrast, the dependence of the sparsity on dynamical state is much stronger, increasing by a factor of $\sim$60% from the 1/3 most relaxed to the 1/3 most disturbed objects, an effect significant at more than 3 sigma. This is the first observational evidence that the shape of the integrated total mass profile in massive Clusters is principally governed by the dynamical state, and is only mildly dependent on redshift. We discuss the consequences for the comparison between observations and theoretical predictions.
Dennis Zaritsky - One of the best experts on this subject based on the ideXlab platform.
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strong and weak lensing united iii measuring the mass distribution of the merging galaxy Cluster 1es 0657 558
The Astrophysical Journal, 2006Co-Authors: Marusa Bradac, Douglas Clowe, Anthony H Gonzalez, Phil Marshall, W Forman, Christine Jones, M Markevitch, Scott W Randall, T Schrabback, Dennis ZaritskyAbstract:The galaxy Cluster 1E0657-56 (z = 0.296) is remarkably well-suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multi-color, high-resolution HST ACS images allow detection of many more arc candidates than were previously known, especially around the subCluster. Using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. Combining this information with shape measurements of ''weakly'' lensed sources, we derive a high-resolution, absolutely-calibrated mass map, using no assumptions regarding the physical properties of the Underlying Cluster potential. This map provides the best available quantification of the total mass of the central part of the Cluster. We also confirm the result from Clowe et al. (2004, 2006a) that the total mass does not trace the baryonic mass.
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strong and weak lensing united iii measuring the mass distribution of the merging galaxy Cluster 1e0657 56
arXiv: Astrophysics, 2006Co-Authors: Marusa Bradac, Douglas Clowe, Anthony H Gonzalez, Phil Marshall, W Forman, Christine Jones, M Markevitch, Scott W Randall, T Schrabback, Dennis ZaritskyAbstract:The galaxy Cluster 1E0657-56 (z = 0.296) is remarkably well-suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multi-color, high-resolution HST ACS images allow detection of many more arc candidates than were previously known, especially around the subCluster. Using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. Combining this information with shape measurements of "weakly" lensed sources, we derive a high-resolution, absolutely-calibrated mass map, using no assumptions regarding the physical properties of the Underlying Cluster potential. This map provides the best available quantification of the total mass of the central part of the Cluster. We also confirm the result from Clowe et al. (2004,2006a).
I Bartalucci - One of the best experts on this subject based on the ideXlab platform.
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the most massive galaxy Clusters m2c across cosmic time link between radial total mass distribution and dynamical state
Astronomy and Astrophysics, 2019Co-Authors: I Bartalucci, M Arnaud, G W Pratt, J Democles, Lorenzo LovisariAbstract:We study the dynamical state and the integrated total mass profiles of 75 massive (M500 > 5 × 1014 M⊙) Sunyaev–Zeldovich(SZ)-selected Clusters at 0.08 0.9. Using XMM-Newton imaging observations, we characterise the dynamical state with the centroid shift ⟨w⟩, the concentration CSB, and their combination, M, which simultaneously probes the core and the large-scale gas morphology. Using spatially resolved spectroscopy and assuming hydrostatic equilibrium, we derive the total integrated mass profiles. The mass profile shape is quantified by the sparsity, that is the ratio of M500 to M2500, the masses at density contrasts of 500 and 2500, respectively. We study the correlations between the various parameters and their dependence on redshift. We confirm that SZ-selected samples, thought to most accurately reflect the Underlying Cluster population, are dominated by disturbed and non-cool core objects at all redshifts. There is no significant evolution or mass dependence of either the cool core fraction or the centroid shift parameter. The M parameter evolves slightly with z, having a correlation coefficient of ρ = −0.2 ± 0.1 and a null hypothesis p-value of 0.01. In the high-mass regime considered here, the sparsity evolves minimally with redshift, increasing by 10% between z 0.55, an effect that is significant at less than 2σ. In contrast, the dependence of the sparsity on dynamical state is much stronger, increasing by a factor of ∼60% from the one third most relaxed to the one third most disturbed objects, an effect that is significant at more than 3σ. This is the first observational evidence that the shape of the integrated total mass profile in massive Clusters is principally governed by the dynamical state and is only mildly dependent on redshift. We discuss the consequences for the comparison between observations and theoretical predictions.
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the most massive galaxy Clusters m2c across cosmic time link between radial total mass distribution and dynamical state
arXiv: Cosmology and Nongalactic Astrophysics, 2019Co-Authors: I Bartalucci, M Arnaud, G W Pratt, J Democles, Lorenzo LovisariAbstract:We study the dynamical state and the integrated total mass profiles of 75 massive (M500 > 5 e+14 M_sun) SZ-selected Clusters at 0.08 0.9. Using XMM imaging observations, we characterise the dynamical state with the centroid shift, the concentration, and their combination, M, which simultaneously probes the core and the large scale gas morphology. Using spatially-resolved spectroscopy and assuming hydrostatic equilibrium, we derive the total integrated mass profiles. The mass profile shape is quantified by the sparsity, the ratio of M500 to M2500, the masses at density contrast 500 and 2500, respectively. We study the correlations between the various parameters and their dependence on redshift. We confirm that SZ-selected samples, thought to reflect most closely the Underlying Cluster population, are dominated by disturbed and non-cool core objects at all z. There is no significant evolution or mass dependence of either the cool core fraction or the centroid shift parameter. The M parameter evolves slightly with z, having a correlation coefficient of rho= -0.2 $\pm$ 0.1 and a null hypothesis p-value of 0.01. In the high mass regime considered here, the sparsity evolves minimally with redshift, increasing by 10% between z 0.55, an effect significant at less than 2 sigma. In contrast, the dependence of the sparsity on dynamical state is much stronger, increasing by a factor of $\sim$60% from the 1/3 most relaxed to the 1/3 most disturbed objects, an effect significant at more than 3 sigma. This is the first observational evidence that the shape of the integrated total mass profile in massive Clusters is principally governed by the dynamical state, and is only mildly dependent on redshift. We discuss the consequences for the comparison between observations and theoretical predictions.
Marusa Bradac - One of the best experts on this subject based on the ideXlab platform.
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strong and weak lensing united iii measuring the mass distribution of the merging galaxy Cluster 1es 0657 558
The Astrophysical Journal, 2006Co-Authors: Marusa Bradac, Douglas Clowe, Anthony H Gonzalez, Phil Marshall, W Forman, Christine Jones, M Markevitch, Scott W Randall, T Schrabback, Dennis ZaritskyAbstract:The galaxy Cluster 1E0657-56 (z = 0.296) is remarkably well-suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multi-color, high-resolution HST ACS images allow detection of many more arc candidates than were previously known, especially around the subCluster. Using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. Combining this information with shape measurements of ''weakly'' lensed sources, we derive a high-resolution, absolutely-calibrated mass map, using no assumptions regarding the physical properties of the Underlying Cluster potential. This map provides the best available quantification of the total mass of the central part of the Cluster. We also confirm the result from Clowe et al. (2004, 2006a) that the total mass does not trace the baryonic mass.
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strong and weak lensing united iii measuring the mass distribution of the merging galaxy Cluster 1e0657 56
arXiv: Astrophysics, 2006Co-Authors: Marusa Bradac, Douglas Clowe, Anthony H Gonzalez, Phil Marshall, W Forman, Christine Jones, M Markevitch, Scott W Randall, T Schrabback, Dennis ZaritskyAbstract:The galaxy Cluster 1E0657-56 (z = 0.296) is remarkably well-suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multi-color, high-resolution HST ACS images allow detection of many more arc candidates than were previously known, especially around the subCluster. Using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. Combining this information with shape measurements of "weakly" lensed sources, we derive a high-resolution, absolutely-calibrated mass map, using no assumptions regarding the physical properties of the Underlying Cluster potential. This map provides the best available quantification of the total mass of the central part of the Cluster. We also confirm the result from Clowe et al. (2004,2006a).
