Related papers: Does the galaxy NGC1052-DF2 falsify Milgromian dyn…
Massive gravity provides a natural solution for the dark energy problem of cosmology and is also a candidate for resolving the dark matter problem. I demonstrate that, assuming reasonable scaling relations, massive gravity can provide for…
We present detailed semi-analytical models for the formation of disk galaxies both in a Universe dominated by dark matter (DM), and in one for which the force law is given by modified Newtonian dynamics (MOND). We tune the models to fit the…
Dynamical friction works very differently for Newtonian gravity with dark matter and in modified Newtonian dynamics (MOND). While the absence of dark matter considerably reduces the friction in major galaxy mergers, analytic calculations…
The missing gravity in galaxies requires dark matter, or alternatively a modification of gravity or inertia. These theoretical possibilities of fundamental importance may be distinguished by the statistical relation between the observed…
I discuss open theoretical questions pertaining to the modified dynamics (MOND)--a proposed alternative to dark matter, which posits a breakdown of Newtonian dynamics in the limit of small accelerations. In particular, I point the reasons…
The line of sight velocity dispersion of the ultra-diffuse galaxies (UDGs) NGC1052-DF2 and NGC1052-DF4 have been reasonably explained only with the baryonic matter, without requiring any dark matter contribution. The comparable ratio…
MONDian dark matter (MDM) is a new form of dark matter quantum that naturally accounts for Milgrom's scaling, usually associated with modified Newtonian dynamics (MOND), and theoretically behaves like cold dark matter (CDM) at cluster and…
The discrepancy between dynamical mass measures of objects such as galaxies and the observed distribution of luminous matter in the universe is typically explained by invoking an unseen ``dark matter'' component. Dark matter must…
In this work the phenomenology of models possessing a non-minimal coupling between matter and geometry is discussed, with a particular focus on the possibility of describing the flattening of the galactic rotation curves as a dynamically…
Within the standard cosmological scenario the Universe is found to be filled by obscure components (dark matter and dark energy) for ~95% of its energy budget. In particular, almost all the matter content in the Universe is given by dark…
Gravitational potentials in the cosmos are deeper than expected from observed visible objects, a phenomenon usually attributed to dark matter, presumably in the form of a new fundamental particle. Until such a particle is observed, the jury…
While most dwarf galaxies are strongly dark matter dominated, two remarkable objects in the NGC 1052 field, DF2 and DF4, appear to lack dark matter. DF2 and DF4 were recently found to be part of a trail of low luminosity galaxies that…
The recent "bullet-dwarf" model proposes that high-velocity collisions between dwarf galaxies can produce stellar systems with overluminous globular clusters (GCs) and a deficiency of dark matter, as observed in the NGC 1052 group galaxies…
We propose to determine the stellar velocity dispersions of globular clusters in the outer halo of the Milky Way in order to decide whether the dynamics of the universe on large scales is governed by dark matter or modified Newtonian…
Modern astrophysical and cosmological models are faced with two severe theoretical difficulties, that can be summarized as the dark energy and the dark matter problems. Relative to the former, it has been stated that cosmology has entered a…
We investigate the possibility that the observed behavior of test particles outside galaxies, which is usually explained by assuming the presence of dark matter, is the result of the dynamical evolution of particles in higher dimensional…
The MOND paradigm posits a departure from standard Newtonian dynamics, and from General Relativity, in the limit of small accelerations. The resulting modified dynamics aim to account for the mass discrepancies in the universe without…
Galaxies are the basic structural element of the universe; galaxy formation theory seeks to explain how these structures came to be. I trace some of the foundational ideas in galaxy formation, with emphasis on the need for non-baryonic cold…
It is now, generally, believed that the presence of some form of dark matter is essential to explain the flat rotation curves of galaxies, and anomalous large velocities of galaxies in the clusters and superclusters. This dark matter turns…
The Lambda-CDM cosmological model is succesful at reproducing various independent sets of observations concerning the large-scale Universe. This model is however currently, and actually in principle, unable to predict the gravitational…