Related papers: Galactic Mass-to-Light Ratios With Superfluid Dark…
We argue that combined observations of galaxy rotation curves and gravitational lensing not only allow the deduction of a galaxy's mass profile, but also yield information about the pressure in the galactic fluid. We quantify this statement…
The shape and diversity of dwarf galaxy rotation curves is at apparent odds with dark matter halos in a $\Lambda$ Cold Dark Matter ($\Lambda$CDM) cosmology. We use mock data from isolated dwarf galaxy simulations to show that this owes to…
We have studied a large number of elliptical galaxies and found a correlation between their dark matter content and the ellipticity of their visible shape. The galaxies were strictly selected so that only typical medium-size elliptical…
We derive probability density functions for the projected axial ratios of the real and mock 2PIGG galaxy groups, and use this data to investigate the intrinsic three dimensional shape of the dark matter ellipsoids that they trace. As well…
The tidal deformability and the radius of neutron stars are observables, which have been used to constrain the neutron star equation of state and explore the composition in neutron stars. We investigated the radius and tidal deformability…
A wealth of astronomical data indicate the presence of mass discrepancies in the Universe. The motions observed in a variety of classes of extragalactic systems exceed what can be explained by the mass visible in stars and gas. Either (i)…
The existence of the flat rotation curves of galaxies is still perplexing. The dark matter paradigm was proposed long ago to solve this conundrum; however, this proposal is still under debate. In this paper, we search for universal…
This work observationally addresses the relative distribution of total and optically luminous matter in galaxy clusters by computing the radial profile of the stellar-to-total mass ratio. We adopt state-of-the-art accurate lensing masses…
The evidence of the phenomenon for which, in galaxies, the gravitating mass is distributed differently than the luminous mass, increases as new data become available. Furthermore, this discrepancy is well structured and it depends on the…
Dark Matter (DM) and Modified Newtonian Dynamics (MOND) models of rotationally supported galaxies lead to curves with different geometries in $(g_{N},g_{tot})$-space ($g2$-space). Here $g_{tot}$ is the total acceleration and $g_{N}$ is the…
We fit model spectral energy distributions to each pixel in 67 nearby (<z>=0.0057) galaxies using broadband photometry from the Sloan Digital Sky Survey and GALEX. For each galaxy, we compare the stellar mass derived by summing the mass of…
We present new measurements of scaling laws relating the luminosity of galaxies to the amplitude and shape of their dark matter halos. Early imaging and spectroscopic data from the Sloan Digital Sky Survey are used to make weak lensing…
Despite the success of dark-matter models, unresolved issues require exploring alternatives such as modified gravity theories. In this context, we examine the compatibility of the Hyperconical Modified Gravity (HMG) with galaxy rotation…
Maximum disc decompositions of rotation curves place a dynamical upper limit to the mass attributable to stars in galaxies. The precise definition of this term, however, can be vague and varies in usage. We develop an algorithm to robustly…
We measure the projected density profile, shape and alignment of the stellar and dark matter mass distribution in 11 strong-lens galaxies. We find that the projected dark matter density profile - under the assumption of a Chabrier stellar…
The rotation velocity profiles of galaxies (rotation curves) remain unexpectedly flat at large distances, where visible matter alone should make the rotation velocity decrease with radius. Conventionally, this requires a large amount of…
The missing mass problem has not been solved decisively yet. Observations show that if gravity is to be modified, then the MOND theory is its excellent approximation on galactic scales. MOND suggests an adjustments of the laws of physics in…
How is mass distributed in the Universe? How does it compare with the distribution of light and stars? We address these questions by examining the distribution of mass, determined from weak lensing observations, and starlight, around…
Observations of galaxies suggest a one-to-one analytic relation between the inferred gravity of dark matter at any radius and the enclosed baryonic mass, a relation summarized by Milgrom's law of modified Newtonian dynamics (MOND). However,…
I consider the observed rotation curves of 12 gas-dominated low-surface-brightness galaxies -- objects in which the mass of gas ranges between 2.2 and 27 times the mass of the stellar disk (mean=9.4). This means that, in the usual…