Related papers: Should Elliptical Galaxies Be Idealised as Collisi…
Schwarzschild models of a Plummer sphere were constructed and compared with analytical results to test the robustness of Schwarzschild's method and its efficiency in probing the degeneracy of the solution space. The method was then used to…
It is pointed out that if we allow for the possibility of a multilayered universe, it is possible to maintain exact supersymmetry and arrange, in principle, for the vanishing of the cosmological constant. Superpartner(s) of a known particle…
It is well known that a large fraction of galaxies have cuspy luminosity profiles in their central regions, at least within the observational resolution. In such cases, the often used, simplified, local approximation for the dynamical…
An asymmetry index is derived from ellipse-fitting to galaxy images, that gives weight to faint outer features and is not strongly redshift-dependent. These measures are made on a sample of 13 2MASS QSOs and their neighbour galaxies, and a…
Asymptotically safe theories of gravitation have received great attention in recent times. In this framework an effective action embodying the basic features of the renormalized flow around the non-gaussian fixed point is derived and its…
We critically examine the claim made by Burko and Ori that black holes are expected to form in nonsymmetric gravity and find their analysis to be inconclusive. Their conclusion is a result of the approximations they make, and not a…
A linear Boltzmann equation with nonautonomous collision operator is rigorously derived in the Boltzmann-Grad limit for the deterministic dynamics of a Rayleigh gas where a tagged particle is undergoing hard-sphere collisions with…
A theoretical treatment is presented of kinetic equilibria in accretion discs around compact objects, for cases where the plasma can be considered as collisionless. The plasma is assumed to be axi-symmetric and to be acted on by…
We study semilinear elliptic inequalities with a potential on infinite graphs. Given a distance on the graph, we assume an upper bound on its Laplacian, and a growth condition on a suitable weighted volume of balls. Under such hypotheses,…
We investigate the velocity distribution of elliptical galaxies in the framework of Non-local Gravity. According to this approach, it is possible to recover the fundamental plane of elliptical galaxies without the dark matter hypothesis.…
A recently proposed nonlinear transport equation is used to model bulk viscous cosmologies that may be far from equilibrium, as happens during viscous fluid inflation or during reheating. The asymptotic stability of the de Sitter and…
We numerically simulate gravitational collapse in asymptotically anti-de Sitter spacetimes away from spherical symmetry. Starting from initial data sourced by a massless real scalar field, we solve the Einstein equations with a negative…
Within the context of the standard structure formation scenario, massive present day elliptical galaxies are sometimes thought of as the result of a major merger of spiral systems. Through extensive SPH simulations of merging spirals, we…
The scalar ``cosmon'' field mediating quintessence influences the dynamics of extended objects in the universe. We discuss cosmon lumps -- spherically symmetric solutions for the scalar field coupled to gravity. The two integration…
In this work, we investigate the problem of finite time blow up as well as the upper bound estimates of lifespan for solutions to small-amplitude semilinear wave equations with time dependent damping and potential, and mixed nonlinearities…
We investigate partial symmetry of solutions to semi-linear and quasi-linear elliptic problems with convex nonlinearities, in domains that are either axially symmetric or radially symmetric.
It has recently been argued that single-collapse high-redshift models for elliptical galaxy formation can be rejected because they predict large numbers of very red galaxies at intermediate redshifts which are not seen in deep…
N-body simulations of major spiral-spiral mergers with different mass ratios q <= 4:1 are presented. All mergers lead to spheroidal stellar systems with de Vaucouleurs-like surface density profiles, resembling elliptical galaxies. The…
We prove the non-linear stability of a large class of spherically symmetric equilibrium solutions of both the collisonless Boltzmann equation and of the Euler equations in MOND. This is the first such stability result that is proven with…
The existence of stationary solutions to the Einstein-Vlasov system which are axially symmetric and have non-zero total angular momentum is shown. This provides mathematical models for rotating, general relativistic and asymptotically flat…