Related papers: Dark Matter and Cold Fractal Clouds
The vorticity equation stemming from the modified Navier-Stokes equation gives a solution for a flat profile of the orbital speed of spiral galaxies. Solutions disclose existence of the Gaussian vortex clouds, the coherent vortices with…
A key prediction of the standard cosmological model -- which relies on the assumption that dark matter is cold, i.e. non-relativistic at the epoch of structure formation -- is the existence of a large number of dark matter substructures on…
After a brief introduction to standard cosmology and the dark matter problem in the the Universe, we consider a self-gravitating noninteracting fermion gas at nonzero temperature as a model for the dark matter halo of the Galaxy. This…
Cold Dark Matter (CDM) has become the standard modern theory of cosmological structure formation. Its predictions appear to be in good agreement with data on large scales, and it naturally accounts for many properties of galaxies. But…
Measuring the density profile and mass concentration of dark-matter haloes is a key test of the standard cold dark matter paradigm. Such objects are dark and thus challenging to characterise, but they can be studied via gravitational…
The severity of the mass discrepancy in spiral galaxies is strongly correlated with the central surface brightness of the disk. Progressively lower surface brightness galaxies have ever larger mass discrepancies. No other parameter…
As cosmology has entered a phase of precision experiments, the content of the universe has been established to contain interesting and not yet fully understood components, namely dark energy and dark matter. While the cause and exact nature…
The entropies of the known entities in the universe add to a total which is some twenty orders of magnitude below the holographic limit. Based on an assumption that the entropies should saturate the limit, we suggest that there exists dark…
We have studied a mass model for spiral galaxies in which the dark matter surface density is a scaled version of the observed HI surface density. Applying this mass model to a sample of 24 spiral galaxies with reliable rotation curves one…
The properties of nearby galaxies that can be observed in great detail suggest that a better theory rather than cold dark matter (CDM) would describe in a better way a mechanism by which matter is more rapidly gathered into large-scale…
It is shown that the vacuum condensate induced by many phenomena behaves as a perfect fluid which, under particular conditions, has zero or negative pressure. In particular, the condensates of thermal states, of fields in curved space and…
This work investigates the dark matters structures that form on the smallest cosmological scales. We find that the types and abundances of structures which form at approximately Earth-mass scales are very sensitive to the nature of dark…
Although well established observations on cosmological, cluster, and galactic scales strongly suggest the existence of dark matter (DM), our understanding of its non-gravitational properties is still lacking. I review basic aspects of…
The standard framework within which cosmological measurements are confronted and interpreted nowadays, called Lambda Cold Dark Matter, presents a Universe dominated by unknown forms of energy and matter. My Thesis is devoted to investigate…
Dark matter particles populating our galactic halo could be directly detected by measuring their scattering off target nuclei or electrons in a suitable detector. As this interaction is expected to occur with very low probability and would…
The presence of unseen halos of ``dark matter'' has long been inferred from the high rotation speeds of gas and stars in the outer parts of spiral galaxies$^{1}$. The volume density of this dark matter decreases less quickly from the…
The astronomical dark matter could be made of weakly interacting and massive particles. If so, these species would be abundant inside the Milky Way, where they would continuously annihilate and produce cosmic rays. Those annihilation…
The majority of the matter in the universe is still unidentified and under investigation by both direct and indirect means. Many experiments searching for the recoil of dark-matter particles off target nuclei in underground laboratories…
We describe the first results from two observational projects aimed at measuring the amount and spatial distribution of dark matter in distant early-type galaxies (E/S0s) and clusters of galaxies. At the galaxy scale, the Lenses Structure…
The search for dark matter is a very wide and active field of research. Many potential hints of dark matter have appeared recently which led to a burst of theoretical activity and model building. I necessarily concentrate here only in some…