Related papers: Testing Newtonian gravity in the low acceleration …
Globular clusters have proven to be essential to our understanding of many important astrophysical phenomena. Here we analyse spectroscopic observations of ten Halo globular clusters to determine their dark matter content, their tidal…
Using numerical simulations of the formation and evolution of stellar clusters within molecular clouds, we show that the stars in clusters formed within collapsing molecular cloud clumps exhibit a constant velocity dispersion regardless of…
We study velocity moments of elliptical galaxies in the Coma cluster using Jeans equations. The dark matter distribution in the cluster is modelled by a generalised formula based upon the results of cosmological N-body simulations. Its…
Velocities in stable circular orbits about galaxies, a measure of centripetal gravitation, exceed the expected Kepler/Newton velocity as orbital radius increases. Standard LCDM attributes this anomaly to galactic dark matter. McGaugh et al…
The recent detection of Doppler shifts of X-ray spectral lines in the intracluster gas of the Centaurus and Perseus clusters of galaxies with ASCA has raised the question of the frequency of such velocity gradients and their relation to…
By studying the chameleon gravity on galaxy scales, we investigate the effects of the chameleon dark matter. To perform this task, we consider the dynamics of the chameleon scalar field in the region of galactic halos in static spherically…
The dynamics of globular cluster systems (GCSs) around galaxies are often used to assess the total enclosed mass, and even to constrain the dark matter distribution. The globular cluster system of a galaxy is typically assumed to be in…
Radial velocities are presented for a new sample of globular clusters in the outer halo of M87 at a distance of 300 to 540 arcsec (24 to 43 kpc) from the center of this galaxy. These are used to augment our previously published data and an…
The controversy "dark matter vs. modified gravity" constitutes a major topic of discussion. It was proposed that dynamical friction could be used to discriminate between the two alternatives. Analytic calculations indicate that, with…
As a first step towards a comprehensive investigation of stellar motions within globular clusters, we present here the results of a study of stellar orbits in a mildly triaxial globular cluster that follows a circular orbit inside a galaxy.…
By means of N-body/hydrodynamical simulations we model the evolution of a primordial 10^{8} solar masses density peak which ends up in an object closely resembling the present day globular cluster Omega Centauri. We succeed to reproduce the…
Under a MONDian view, astrophysical systems are expected to follow Newtonian dynamics whenever the local acceleration is above the critical $a_{0}=1.2 \times 10^{-10} m s^{-2}$, and enter a modified regime for accelerations below this…
Typical stars in the Milky Way galaxy have velocities of hundreds of kilometres per second and experience gravitational accelerations of $\sim 10^{-10}$ m s$^{-2}$, resulting in velocity changes of a few centimetres per second over a…
The globular cluster Omega Centauri (NGC 5139) is the most massive and brightest cluster in our Galaxy. It has also a moderately high mass to light ratio (3.6) and an anomalous flattening (0.83) for a globular cluster. This cluster is also…
Stretching of the Newtonian potential (NP) at early epochs is investigated and it is shown that observed effects, usually ascribed to a dark matter, can by explained by such stretching only. Increasing by time radius of the…
Modifications to Newtonian dynamics at low accelerations have long been proposed as an alternative to dark matter to explain galaxy rotation curves. More recently, similar corrections have been invoked to interpret anomalies in…
Globular clusters are an excellent laboratory for stellar population and dynamical research. Recent studies have shown that these stellar systems are not as simple as previously assumed. With multiple stellar populations as well as outer…
Internal rotation is considered to play a major role in the dynamics of some globular clusters. However, in only few cases it has been studied by quantitative application of realistic and physically justified global models. Here we present…
The rotational properties of centrally condensed, turbulent molecular cloud cores with velocity fields that are characterized by Gaussian random fields are investigated. It is shown that the observed line width-size relationship can be…
$\omega$ Centauri is considered the most massive globular cluster of the Milky Way and likely the former nuclear star cluster of a galaxy accreted by the Milky Way. It is speculated to contain an intermediate-mass black hole (IMBH) from…