Related papers: The Hubble stream near a massive object: the exact…
Gravitational lensing in clusters of galaxies is an efficient tool to probe the mass distribution of galaxies and clusters, high redshift objects thanks to the gravitational amplification, and the geometry of the universe. We review some…
Flat rotation curves follow from elongated Dark Matter distributions, as shown by our earlier competitive fits to the SPARC database. Intending to probe that distortion of the DM halo one needs observables not contained by the galactic…
In this talk I focus on how the modelling of the mass-observable relation and the halo mass function can impact the accuracy and precision of cosmological constraints inferred from galaxy clusters. I present a new analysis of clusters…
By virtue of their high galaxy space densities and their large spatial separations, clusters are efficient and accurate tracers of the large-scale density and velocity fields. Substantial progress has been made over the past decade in the…
The physical nature of the very local (<3 Mpc) Hubble flow is studied on the basis of the recent high precision observations in the Local Volume. A model including both analytical treatment and computer simulations describes the flow…
Hierarchical clustering represents the favoured paradigm for galaxy formation throughout the Universe; due to its proximity, the Magellanic system offers one of the few opportunities for astrophysicists to decompose the full six-dimensional…
As the Universe expands, the redshift of distant sources changes with time. Here we discuss gravitational lensing phenomena that are consequence of the redshift drift between lensed source, gravitational lens, and observer. When the source…
We present an analysis of the mechanics of thin streams, which are formed following the tidal disruption of cold, low-mass clusters in the potential of a massive host galaxy. The analysis makes extensive use of action-angle variables, in…
Peculiar velocities change the expansion rate of any observer moving relative to the smooth Hubble flow. As a result, observers in a galaxy like our Milky Way can experience accelerated expansion within a globally decelerating universe,…
In this paper, it is shown that in interaction with an oscillating bubbles cluster the fluid becomes inhomogeneous. The radial variation of the acoustic refractive index of the fluid generates an acoustic lens with spherical symmetry. When…
Recent progress in the measurement of relative distances to galaxies has been quite substantial, and catalogs of 3000 galaxies with distances are soon to become available. The peculiar {\it velocity} field (deviations from Hubble flow)…
We study the effect of dynamical friction on globular clusters and on the stars evaporated from the globular clusters (stellar streams) moving in a galactic halo. Due to dynamical friction, the position of a globular cluster (GC) as a…
We have obtained radial velocity measurements for stars in two, widely-separated fields in the Anticenter Stream. Combined with SDSS/USNO-B proper motions, the new measurements allow us to establish that the stream is on a nearly circular,…
Granular particles vibrated in a fluid have been found to exhibit self-organization with attractive and repulsive interactions between the particles. These interactions have been attributed to the steady streaming flow around oscillating…
Gravitational lensing provides an efficient tool for the investigation of matter structures, independent of the dynamical or hydrostatic equilibrium properties of the deflecting system. However, it depends on the kinematic status. In fact,…
The tidal disruption of stars in the vicinity of massive black holes is discussed in the context of $\Lambda$-gravity. The latter provides an explanation to the Hubble tension as a possible consequence of two Hubble flows, the local and…
A statistical description of heavy particles suspended in incompressible rough self-similar flows is developed. It is shown that, differently from smooth flows, particles do not form fractal clusters. They rather distribute inhomogeneously…
We search for acoustic analogues of a spherical symmetric black hole with a pointlike source. We show that the gravitational system has a dynamical counterpart in the constrained, steady motion of a fluid with a planar source. The equations…
The effect of capture of a cosmic object by the central gravitational field of a galaxy cluster is described in the expanding Universe. The cosmic evolution can be the origin of the capture explaining formation of galaxies and their…
The mass derived from gravitational lensing reflects the total mass contained in the lensing system, independent of the specific matter contents and states. A comparison of the dynamical masses from hydrostatic equilibrium with the…