0000000000790135

AUTHOR

Riccardo Valdarnini

showing 3 related works from this author

Einstein, Planck and Vera Rubin: Relevant Encounters Between the Cosmological and the Quantum Worlds

2021

In Cosmology and in Fundamental Physics there is a crucial question like: where the elusive substance that we call Dark Matter is hidden in the Universe and what is it made of? that, even after 40 years from the Vera Rubin seminal discovery [1] does not have a proper answer. Actually, the more we have investigated, the more this issue has become strongly entangled with aspects that go beyond the established Quantum Physics, the Standard Model of Elementary particles and the General Relativity and related to processes like the Inflation, the accelerated expansion of the Universe and High Energy Phenomena around compact objects. Even Quantum Gravity and very exotic Dark Matter particle candid…

High Energy Physics - TheoryGeneral Physics and AstronomyNature of dark matter01 natural sciencesGeneral Relativity and Quantum CosmologyCosmologyClassical vs quantum cosmologyHigh Energy Physics - Phenomenology (hep-ph)010303 astronomy & astrophysicsQuantumMathematical PhysicsQuantum gravity and cosmologyPhysicsModification of general relativityChaplygin Gaslcsh:QC1-999CosmologyHigh Energy Physics - PhenomenologyExpansion of the UniversesymbolsGeneral RelativityGeneral relativityMaterials Science (miscellaneous)BiophysicsFOS: Physical sciencesGeneral Relativity and Quantum Cosmology (gr-qc)Metric expansion of spacesymbols.namesakeTheory of relativitySettore FIS/05 - Astronomia e Astrofisica0103 physical sciencesDark matterddc:530Cosmological ModelsPhysical and Theoretical ChemistryPlanckEinsteindark matter; galaxies; nature of dark matter; beyond standard model; modification of general relativity; quantum gravity and cosmology; expansion of the Universe010308 nuclear & particles physicsFísicaGalaxiesAstrophysics - Astrophysics of GalaxiesCosmosEpistemologyHigh Energy Physics - Theory (hep-th)quantum gravityAstrophysics of Galaxies (astro-ph.GA)Quantum gravityBeyond standard modellcsh:Physics
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Is there any scaling in the cluster distribution?

1994

We apply fractal analysis methods to investigate the scaling properties in the Abell and ACO catalogs of rich galaxy clusters. We also discuss different technical aspects of the method when applied to data sets with small number of points as the cluster catalogs. Results are compared with simulations based on the Zel'dovich approximation. We limit our analysis to scales less than 100 $\hm$. The cluster distribution show a scale invariant multifractal behavior in a limited scale range. For the Abell catalog this range is 15--60$\hm$, while for the ACO sample it extends to smaller scales. Despite this difference in the extension of the scale--range where scale--invariant clustering takes plac…

Scale (ratio)FOS: Physical sciencesAstrophysics::Cosmology and Extragalactic AstrophysicsCOMPUTERIZED SIMULATIONAstrophysicsSTATISTICAL CORRELATIONFractalSCALING LAWSCluster (physics)Statistical physicsMATHEMATICAL MODELSScalingGalaxy clusterPhysicsASTRONOMICAL CATALOGSAstrophysics (astro-ph)ERROR ANALYSISAstronomy and AstrophysicsMultifractal systemScale invarianceFractal analysisFRACTALSSpace and Planetary ScienceASTRONOMICAL MODELSCLUSTER ANALYSISCOSMOLOGYGALACTIC CLUSTERS
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A global descriptor of spatial pattern interaction in the galaxy distribution

1997

We present the function J as a morphological descriptor for point patterns formed by the distribution of galaxies in the Universe. This function was recently introduced in the field of spatial statistics, and is based on the nearest neighbor distribution and the void probability function. The J descriptor allows to distinguish clustered (i.e. correlated) from ``regular'' (i.e. anti-correlated) point distributions. We outline the theoretical foundations of the method, perform tests with a Matern cluster process as an idealised model of galaxy clustering, and apply the descriptor to galaxies and loose groups in the Perseus-Pisces Survey. A comparison with mock-samples extracted from a mixed d…

PhysicsStructure formationAstrophysics (astro-ph)FOS: Physical sciencesAstronomy and AstrophysicsProbability density functionAstrophysicsFunction (mathematics)Astrophysics::Cosmology and Extragalactic AstrophysicsAstrophysicsGalaxyField (geography)k-nearest neighbors algorithmSpace and Planetary ScienceStatistical physicsCluster analysisSpatial analysisAstrophysics::Galaxy Astrophysics
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