15,495 research outputs found
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' -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
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