SMART: A new implementation of Schwarzschild's Orbit Superposition technique for triaxial galaxies and its application to an N-body merger simulation

Abstract

We present SMART, a new 3D implementation of the Schwarzschild Method and its application to a triaxial N-body merger simulation. SMART fits full line-of-sight velocity distributions (LOSVDs) to determine the viewing angles, black hole, stellar and dark matter (DM) masses and the stellar orbit distribution of galaxies. Our model uses a 5D orbital starting space to ensure a representative set of stellar trajectories adaptable to the integrals-of-motion space and it is designed to deal with non-parametric stellar and DM densities. SMART's efficiency is demonstrated by application to a realistic N-body merger simulation including supermassive black holes which we model from five different projections. When providing the true viewing angles, 3D stellar luminosity profile and normalized DM halo, we can (i) reproduce the intrinsic velocity moments and anisotropy profile with a precision of ~1% and (ii) recover the black hole mass, stellar mass-to-light ratio and DM normalization to better than a few percent accuracy. This precision is smaller than the currently discussed differences between initial-stellar-mass functions and scatter in black hole scaling relations. Further tests with toy models suggest that the recovery of the anisotropy in triaxial galaxies is almost unique when the potential is known and full LOSVDs are fitted. We show that orbit models even allow the reconstruction of full intrinsic velocity distributions, which contain more information than the classical anisotropy parameter. Surprisingly, the orbit library for the analysed N-body simulation's gravitational potential contains orbits with net rotation around the intermediate axis that is stable over some Gyrs.

32 Pages, 30 Figures, accepted by MNRAS

References in corpus (23)

• Properties of galaxies reproduced by a hydrodynamic simulation
• The SAURON project -- IX. A kinematic classification for early-type galaxies
• A systematic variation of the stellar initial mass function in early-type galaxies
• The SAURON project -- X. The orbital anisotropy of elliptical and lenticular galaxies: revisiting the (V/sigma,epsilon) diagram with integral-field stellar kinematics
• Evolutionary stellar population synthesis with MILES - II. Scaled-solar and α-enhanced models
• Triaxial orbit based galaxy models with an application to the (apparent) decoupled core galaxy NGC 4365
• How Mergers May Affect The Mass Scaling Relations Between Black Holes, Galaxies, and Other Gravitationally Bound Systems
• The influence of gas on the structure of merger remnants
• Equal- and unequal-mass mergers of disk and elliptical galaxies with black holes
• Implementing Few-Body Algorithmic Regularization with Post-Newtonian Terms
• NMAGIC: Fast Parallel Implementation of a Chi-Squared-Made-to-Measure Algorithm for Modelling Observational Data
• The SINFONI Nearby Elliptical Lens Locator Survey: Discovery of two new low-redshift strong lenses and implications for the initial mass function in giant early-type galaxies
• Algorithmic regularization with velocity-dependent forces
• Dissipation and the Fundamental Plane: Observational Tests
• The stellar initial mass function of early type galaxies from low to high stellar velocity dispersion: homogeneous analysis of ATLAS${}^{3D}$ and Sloan Lens ACS galaxies
• Axisymmetric orbit models of N-body merger remnants: a dependency of reconstructed mass on viewing angle
• Stellar orbits in cosmological galaxy simulations: the connection to formation history and line-of-sight kinematics
• Evaluating the ability of triaxial Schwarzschild modelling to estimate properties of galaxies from the Illustris simulation
• Orbital Instabilities in a Triaxial Cusp Potential
• Shapes of Stellar Systems and Dark Halos from Simulations of Galaxy Major Mergers
• Constraining black hole masses from stellar kinematics by summing over all possible distribution functions
• Non-parametric Triaxial Deprojection of Elliptical Galaxies
• Three-dimensional Keplerian orbit-superposition models of the nucleus of M31

Cited by in corpus (14)

• MaNGA DynPop -- I. Quality-assessed stellar dynamical modelling from integral-field spectroscopy of 10K nearby galaxies: a catalogue of masses, mass-to-light ratios, density profiles and dark matter
• The SAMI Galaxy Survey: The internal orbital structure and mass distribution of passive galaxies from triaxial orbit-superposition Schwarzschild models
• The two phases of core formation -- orbital evolution in the centres of ellipticals with supermassive black hole binaries
• The Black Hole Mass of NGC 4151 from Stellar Dynamical Modeling
• The SAMI Galaxy Survey: Environmental analysis of the orbital structures of passive galaxies
• Dynamical modelling of the twisted galaxy PGC 046832
• The dynamical structure of broken power-law and double power-law models for dark matter haloes
• The isotropic center of NGC 5419 -- A core in formation?
• Detailed shapes of the line-of-sight velocity distributions in massive early-type galaxies from non-parametric spectral models
• Accuracy and precision of triaxial orbit models II: Viewing angles, shape and orbital structure
• Triaxial Schwarzschild Models of NGC 708: a 10-billion solar mass black hole in a low dispersion galaxy with a Kroupa IMF
• SpheCow: flexible dynamical models for galaxies and dark matter haloes
• Self-consistent dynamical models with a finite extent -- II. Radially truncated models
• Self-consistent dynamical models with a finite extent -- I. The uniform density sphere