Made-to-measure Dynamical Modeling of Galaxies with NMAGIC
IntroductionThe goal of dynamical modeling is to recover from observational data the distribution of orbits for the galaxy's stars, and the gravitational potential in which they move. Through dynamical modeling, one can determine the mass of the supermassive black hole in the galaxy's center, or the amount of dark matter in its outskirts. <more on dynamical modeling>
Figure 1: Evolution of an an initially spherical model consisting of 1.8 million particles towards a triaxial target galaxy. The panels show contour plots of the surface brightness distribution. The black solid lines represent the particle model and the red solid lines correspond to the triaxial target galaxy. The left panel compares the initial model with the target galaxy and the right panel shows the final model. The match is excellent.
Figure 2: Comparison of NMAGIC dynamical particle models with kinematic data for NGC 3379. Left: Comparison of axisymmetric and weakly triaxial models with SAURON kinematic data for NGC 3379 (top panel, Shapiro et al. 2006). Following panels are for models A90, D90, DR. Model A90 has all the mass in the stars, while the later two models include a massive halo. Right: Comparison of the radial velocity dispersion profile from the PN.S data (Douglas et al. 2007) with the oblate and weakly triaxial particle models.
See also page on
outer haloes of elliptical galaxies.
de Lorenzi, F., Gerhard, O., Coccato, L., Arnaboldi, M., Capaccioli, M., Douglas, N. G., et al. 2009, MNRAS, 395, 76.
Dearth of dark matter or massive dark halo? Mass-shape-anisotropy degeneracies revealed by NMAGIC dynamical models of the elliptical
galaxy NGC 3379. 2009MNRAS.395...76D
de Lorenzi, F., Gerhard, O., Saglia, R. P., Sambhus, N., Debattista, V. P., Pannella, M., et al. 2008, MNRAS, 385, 1729.
Dark matter content and internal dynamics of NGC 4697: NMAGIC particle models from slit data and planetary nebula velocities. 2008MNRAS.385.1729D
de Lorenzi, F., Debattista, V. P., Gerhard, O., Sambhus, N. 2007, MNRAS, 376, 71.
NMAGIC: a fast parallel implementation of a χ2-made-to-measure algorithm for modelling observational data. 2007MNRAS.376...71D
Bissantz, N., Debattista, V. P., Gerhard, O. 2004, ApJ, 601, L155.
Large-Scale Model of the Milky Way: Stellar Kinematics and the Microlensing Event Timescale Distribution in the Galactic Bulge. 2004ApJ...601L.155B