Shadows of rotating black holes in alternative theories

We briefly review some recent advances in the study of the shadows of rotating black holes in alternative theories. The size and the shape of the shadow depend on the mass and the angular momentum, and they can also depend on other parameters specific of the particular model adopted. As an example, we show the results corresponding to a rotating braneworld black hole.Comment: 6 pages, 3 figures; v2: minor corrections; prepared for the Proceedings of the Fourteenth Marcel Grossmann Meeting (MG14

Shadow of a Kaluza-Klein rotating dilaton black hole

We study the shadow produced by a spinning Kaluza-Klein black hole in Einstein gravity coupled to a Maxwell field and a dilaton. The size and the shape of the shadow depend on the mass, the charge, and the angular momentum. We find that, for fixed values of these parameters, the shadow is slightly larger and less deformed than for its Kerr-Newman counterpart.Comment: 9 pages, 2 figures; v2: improved version, new references adde

On the geometry of some Equivariantly related manifolds

We provide a topological procedure to obtain geometric realizations of both classical and `exotic' $G$-manifolds, such as spheres, bundles over spheres and Kervaire manifolds. As an application, we apply the process known as Cheeger deformations to produce new metrics of both positive Ricci and almost non-negative curvature on such objects.Comment: 25 page

Aging under Shear: Structural Relaxation of a Non-Newtonian Fluid

The influence of an applied shear field on the dynamics of an aging colloidal suspension has been investigated by the dynamic light scattering determination of the density autocorrelation function. Though a stationary state is never observed, the slow dynamics crosses between two different non-equilibrium regimes as soon as the structural relaxation time approaches the inverse shear rate. In the shear dominated regime (at high shear rate values) the structural relaxation time is found to be strongly sensitive to shear rate while aging proceeds at a very slow rate. The effect of shear on the detailed shape of the density autocorrelation function is quantitatively described assuming that the structural relaxation process arises from the heterogeneous superposition of many relaxing units each one independently coupled to shear with a parallel composition rule for timescales.Comment: 5 pages, 5 figure