## Abstract

Galactic nuclei are now generally thought to have density cusps in their centres, and the evidence is mounting that as a consequence they are unlikely to be triaxial. Self-consistent stellar dynamical models of non-axisymmetric cusps would be an interesting counterargument to this conclusion. We consider 2D analogues of triaxial cusps: a sequence of non-axisymmetric, cuspy discs first described by Sridhar & Touma. Scale-free models with potential Phi proportional to r(alpha) are examined in detail. It is shown analytically for 0 < alpha less than or similar to 0.43 that self-consistent models with positive phase-space density do not exist. Numerical solutions of the combined Vlasov and Poisson equations suggest that the whole sequence of models with 0 < alpha < 1 are also unphysical. Together with existing work on cusps, we conclude on purely theoretical grounds that galactic nuclei are not expected to be triaxial.

Original language | English |
---|---|

Pages (from-to) | 407-413 |

Number of pages | 7 |

Journal | Monthly Notices of the Royal Astronomical Society |

Volume | 296 |

Issue number | 2 |

Publication status | Published - 11 May 1998 |

## Keywords

- galaxies, kinematics and dynamics
- SELF-CONSISTENT MODELS
- DARK-MATTER HALOS
- ELLIPTIC GALAXIES
- SHAPES