I review various ideas on MOND cosmology and structure formation beginning with non-relativistic models in analogy with Newtonian cosmology. I discuss relativistic MOND cosmology in the context of Bekenstein’s theory and propose an alternative biscalar effective theory of MOND in which the acceleration parameter, a0 is identified with the cosmic time derivative of a matter coupling scalar field...

MOdified Newtonian Dynamics (MOND) is evolving from an empirical to a decent theory respecting fundamental physics after Bekenstein (2004) showed that lensing and Hubble expansion can be modeled rigourously in a Modified Relativity. The degeneracy of MOND with Dark Matter can be broken if we examine the non-linear MONDian Poisson’s equation in detail. Here we study the effect of tides for a bin...

We present a simple method, based on the deformation of spherically symmetric potentials, to construct explicit axisymmetric and triaxial MOND densitypotential pairs. General guidelines to the choice of suitable deformations, so that the resulting density distribution is nowhere negative, are presented. This flexible method offers for the first time the possibility to study the MOND gravitation...

We compare orbits in a thin axisymmetric disc potential in MOND to those in a thin disc plus near-spherical dark matter halo predicted by a ΛCDM cosmology. Remarkably, the amount of orbital precession in MOND is nearly identical to that which occurs in a mildly oblate CDM Galactic halo (potential flattening q=0.9), consistent with recent constraints from the Sagittarius stream. Since very flatt...

The widely accepted dark matter hypothesis offers a seductive solution to missing mass problems (galaxies, clusters of galaxies, gravitational collapse in structure formation,...). However the physical nature of the Dark Matter itself is still unknown. Alternatively, it has been proposed that apparent dynamical evidence of dark matter is due to a modification of Newton’s law of gravitation. Her...

The observed dynamics of gas and stars on galactic and larger scales cannot be accounted for by self-gravity, indicating that there are large quantities of unseen matter, or that gravity is non-Newtonian in these regimes. Milgrom’s MOdified Newtonian Dynamics (MOND) postulates that Newton’s laws are modified at very low acceleration, and can account for the rotation curves of galaxies and some ...

The cluster of galaxies MS2137-23 presents the most constrained lensing configuration of gravitational images ever detected in a distant cluster of galaxies. With a set of two arc systems with known redshifts and many other arclets spread between ≈ 30 h−1 kpc and 1 h−1 Mpc, MS2137-27 is well suited to probe its mass profile and to challenge theoretical expectations from CDM scenario with more s...

We summarize the status of Modified Newtonian Dynamics (MOND) in galaxy clusters. The observed acceleration is typically larger than the acceleration threshold of MOND in the central regions, implying that some dark matter is necessary to explain the mass discrepancy there. A plausible resolution of this issue is that the unseen mass in MOND is in the form of ordinary neutrinos with masses just...

To test modified Newtonian dynamics (MOND) on galactic scales, we study six strong gravitational lensing early-type galaxies from the CASTLES sample. Comparing the total mass (from lensing) with the stellar mass content (from a comparison of photometry and stellar population synthesis), we conclude that strong gravitational lensing on galactic scales requires a significant amount of dark matter...

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 dynamics (MOND). We show that, for a number of Galactic globular clusters, both the internal and the external accelerations are significantly below the critical ac...