2,278 research outputs found
Shadows and photon rings of binary black holes
In this paper we present the images of binary black holes using the
Majumdar-Papapetrou multiblack hole solution, depending on the parameters of
the problem: the mass of black holes, the distance between them, and the
inclination of the observer. The images consists of a shadows and photon rings.
We find that a photon ring structure appears between black holes. The
trajectories of the photons are calculated
Thick fluid disks around binary black holes
A model of a thick fluid disk around a binary black hole is considered. A
binary black hole is described by the Majumdar-Papapetrou solution. The
hydrodynamic equations in this metric are written out. Exact analytical
solutions are presented. Generalization to the case of a toroidal magnetic
field is carried out
Ultra-hard fluid and scalar field in the Kerr-Newman metric
An analytic solution for the accretion of ultra-hard perfect fluid onto a
moving Kerr-Newman black hole is found. This solution is a generalization of
the previously known solution by Petrich, Shapiro and Teukolsky for a Kerr
black hole. Our solution is not applicable for an extreme black hole due to
violation of the test fluid approximation. We also present a stationary
solution for a massless scalar field in the metric of a Kerr-Newman naked
singularity.Comment: 9 pages, 3 figures, revtex4; v2: presentation improved, figures
added, matches published versio
Billiards with polynomial mixing rates
While many dynamical systems of mechanical origin, in particular billiards,
are strongly chaotic -- enjoy exponential mixing, the rates of mixing in many
other models are slow (algebraic, or polynomial). The dynamics in the latter
are intermittent between regular and chaotic, which makes them particularly
interesting in physical studies. However, mathematical methods for the analysis
of systems with slow mixing rates were developed just recently and are still
difficult to apply to realistic models. Here we reduce those methods to a
practical scheme that allows us to obtain a nearly optimal bound on mixing
rates. We demonstrate how the method works by applying it to several classes of
chaotic billiards with slow mixing as well as discuss a few examples where the
method, in its present form, fails.Comment: 39pages, 11 figue
Adatom incorporation and step crossing at the edges of 2D nanoislands
Adatom incorporation into the ``faceted'' steps bordering the 2D nanoislands
is analyzed. The step permeability and incorporation coefficients are derived
for some typical growth situations. It is shown that the step consisting of
equivalent straight segments can be permeable even in the case of fast egde
migration if there exist factors delaying creation of new kinks. The step
consisting of alternating rough and straight segments may be permeable if there
is no adatom transport between neighboring segments through the corner
diffusion.Comment: 3 pages, one figur
The wave function of a gravitating shell
We have calculated a discrete spectrum and found an exact analytical solution
in the form of Meixner polynomials for the wave function of a thin gravitating
shell in the Reissner-Nordstrom geometry. We show that there is no extreme
state in the quantum spectrum of the gravitating shell, as in the case of
extreme black hole.Comment: 7 pages, 1 figur
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