arXiv subjects
Publications and source records attributed to Ellen Verolme.
We have developed an orbit-based method for constructing triaxial models of elliptical galaxies, which fit their observed surface brightness and kinematics. We have tested the method against analytical models with general distribution functions. Here, we present models that fit integral-field SAURON observations of NGC3379 and NGC4365.
We have developed a method to construct realistic triaxial dynamical models for elliptical galaxies, allowing us to derive best-fitting parameters, such as the mass-to-light ratio and the black hole mass, and to study the orbital structure. We use triaxial theoretical Abel models to investigate the robustness of the method.
The Jeans equations relate the second-order velocity moments to the density and potential of a stellar system. For general three-dimensional stellar systems, there are three equations, but these are not very helpful, as they contain six independent moments. By assuming that the potential is triaxial and of separable Staeckel form, the mixed moments vanish in confocal ellipsoidal coordinates. The three Jeans equations and three remaining non-vanishing moments form a closed system of three highly-symmetric coupled first-order partial differential equations in three variables. They were first derived by Lynden-Bell in 1960, but have resisted solution by standard methods. Here we present the general solution by superposition of singular solutions.
We present the SAURON project, which is aimed at studying the morphology, two-dimensional kinematics and stellar populations of a representative sample of elliptical galaxies and spiral bulges. SAURON, a dedicated integral-field spectrograph that is optimized for wide-field observations and has high throughput, was built in Lyon and is now operated at the WHT 4.2m telescope. At present, we have observed approximately two thirds of the seventy-two sample galaxies with SAURON. A comparison with published long-slit measurements demonstrates that the SAURON-data is of equal or better quality, and provides full two-dimensional coverage. The velocity and velocity dispersion fields exhibit a large variety of morphologies: from simple rotating systems to cylindrical, disky and triaxial velocity fields, bars and decoupled cores. Most of these kinematical signatures do not have counterparts in the light distribution. While some galaxies are consistent with axisymmetry, most are more complex systems than assumed previously. This suggests that the kinematical properties of nearby E/S0 galaxies do not agree with the often assumed simplistic two-family model, in which the giant non-rotating triaxial ellipticals are opposed to the fast-rotating axisymmetric faint ellipticals and S0s.
The SAURON project will deliver two-dimensional spectroscopic data of a sample of nearby early-type galaxies with unprecedented quality. In this paper, we focus on the mapping of their stellar populations using the SAURON data, and present some preliminary results on a few prototypical cases.