222,123 research outputs found
A completely analytical family of dynamical models for spherical galaxies and bulges with a central black hole
We present a family of spherical models for elliptical galaxies and bulges
consisting of a stellar component and a central black hole. All models in this
family share the same stellar density profile, which has a steep central cusp.
The gravitational potential of each models is a linear combination of the
potential generated selfconsistently by the stars and the potential of a
central black hole. The relative importance of these two contributions is a
free parameter in the models. Assuming an isotropic dynamical structure, almost
all kinematical properties of these models can be calculated analytically. In
particular, they form the first simple dynamical models for galaxies with a
central black hole where the distribution function and differential energy
distribution can be written completely in terms of elementary functions only.
We also present various extensions of this family to models with anisotropic
orbital structures. Also for these dynamical models, the distribution function
and its moments can be expressed completely in terms of elementary functions.
This family is useful for a large range of applications, in particular to
generate initial conditions for N-body and hydrodynamical simulations to model
galactic nuclei with a central black hole.Comment: 13 pages, 1 figure, accepted for publication in MNRA
Iteration of meromorphic functions
This paper attempts to describe some of the results obtained in the iteration
theory of transcendental meromorphic functions, not excluding the case of
entire functions. The reader is not expected to be familiar with the iteration
theory of rational functions. On the other hand, some aspects where the
transcendental case is analogous to the rational case are treated rather
briefly here. For example, we introduce the different types of components of
the Fatou set that occur in the iteration of rational functions but omit a
detailed description of these types. Instead, we concentrate on the types of
components that are special to transcendental functions (Baker domains and
wandering domains).Comment: 38 pages. Abstract added in migration. See
http://analysis.math.uni-kiel.de/bergweiler/ for recent comments and
correction
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