1998/12/07 by Luca Ciotti, L. Ciotti, Ciotti, L.
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9812118
4 pages, 0 figures, uses cupconf.sty. To appear on the proceedings of the STScI workshop ``When and how do bulges form and evolve?'' (5-7 October, 1998)
arxiv created 1998/12/07 · openalex publication_date 1998/12/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The properties of the analitycal phase--space distribution function of two-component spherical self-consistent galaxy models, where one density distribution follows the Hernquist profile, and the other a gamma=0 model, with different total masses and core radii (H0 models), presented in Ciotti (1998), are here summarized. A variable amount of radial Osipkov-Merritt orbital anisotropy is allowed in both components. The necessary and sufficient conditions that the model parameters must satisfy in order to correspond to a model where each one of the two distinct components has a positive DF (the so-called model consistency) are analytically derived, together with some results on the more general problem of the consistency of two-component gamma1+gamma2 models. The possibility to add in a consistent way a black hole at the center of radially anisotropic gamma models is also discussed. In particular, it is proved that a globally isotropic Hernquist component is consistent for any mass and core radius of the superimposed gamma=0 halo; on the contrary, only a maximum value of the core radius is allowed to the gamma=0 component when a Hernquist halo is added. The combined effect of halo concentration and orbital anisotropy is successively investigated.