2018/09/30 by John Magorrian
Physics and Astronomy · #Aerospace engineering #Astronomy #Astrophysics #Celestial mechanics #Circular orbit #Classical mechanics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Kinematics #Orbit (dynamics) #Orbital mechanics #Physics #Quantum mechanics #Satellite #Stellar dynamics #Stellar, planetary, and galactic studies #Superposition principle #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stz037
17 pages, MNRAS accepted
openalex publication_date 2019/01/05 · arxiv created 2019/01/21 · arxiv updated 2019/01/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a method for fitting orbit-superposition models to the kinematics of discrete stellar systems when the available stellar sample has been filtered by a known selection function. The fitting method can be applied to any model in which the distribution function is represented as a linear superposition of basis elements with unknown weights. As an example, we apply it to Fritz et al.’s kinematics of the innermost regions of the Milky Way’s nuclear stellar cluster. Assuming spherical symmetry, our models fit a black hole of mass |M_\bullet =(3.76± 0.22)× 106 M_\odot|, surrounded by an extended mass |M_⋆ =(6.57± 0.54)× 106 M_\odot| within |4 \hboxpc|. Within |1 \hboxpc| the best-fitting mass models have an approximate power-law density cusp ρ ∝ r−γ with γ = 1.3 ± 0.3. We carry out an extensive investigation of how our modelling assumptions might bias these estimates: M• is the most robust parameter and γ the least. Internally the best-fitting models have broadly isotropic orbit distributions, apart from a bias towards circular orbits between 0.1 and 0.3 parsec.