Title:	Cusps without chaos
Authors:	Sridhar, S. Touma, Jihad R.
Keywords:	Galaxies Elliptical and lenticular Kinematics and dynamics
Issue Date:	1997
Publisher:	Blackwell Publishing for the Royal Astronomical Society
Citation:	Monthly Notices of the Royal Astronomical Society, 1997, Vol.287, pL1-L4
Abstract:	We present cuspy, non-axisymmetric, scale-free mass models of discs, whose gravitational potentials are of Stackel form in parabolic coordinates. A black hole may be added at the centre, without in any way affecting the Stackel form; the dynamics in these potentials is, of course, fully integrable. The surface density Sigma(disc) proportional to 1/r(gamma), where 0<gamma<1 corresponds to steep cusps for which the central force diverges. Thus cusps, black holes, and non-axisymmetry are not a sure recipe for chaos, as is generally assumed. A new family of orbits, lens orbits, emerges to replace the box orbits of models of elliptical galaxies that have constant-density cores. Loop orbits are conspicuous by their absence. Both lenses and bananas (the other family of orbits) can be elongated in the direction of the density distribution, a property that is favourable for the construction of non-axisymmetric, self-consistent equilibrium models of elliptical galaxies.
Description:	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/4805
ISSN:	0035-8711
Copyright:	1997 Blackwell Publishing for the Royal Astronomical Society
Appears in Collections:	Research Papers (A&A)

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