8 research outputs found
Orbital structure of triaxial galaxies
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.Comment: 2 pages (1 figure), to appear in the proceedings of the IAU Symposium
220 "Dark matter in galaxies", eds. S. Ryder, D.J. Pisano, M. Walker and K.
Freema
Jeans solutions for triaxial galaxies
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.Comment: 8 pages (1 figure), contributed talk at the Athens Workshop on
Galaxies and Chaos, Theory and Observations; Proceedings to appear in
"Galaxies and Chaos", eds. G. Contopoulos and N. Vogli
Probing the stellar populations of early-type galaxies: the SAURON survey
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.Comment: 12 pages, 6 figures. ASP Conference, Galaxies: the Third Dimension,
Cozumel. Version with higher resolution figures available at
http://www-obs.univ-lyon1.fr/eric.emsellem/papers/cozumel_emsellem.ps.g
Two-dimensional kinematics and stellar populations of early-type galaxies: First results from the SAURON survey
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.Comment: 10 pages, 6 figures, conference "galaxies: the third dimension",
cozumel, mexico, 3-7 december 200
Jeans Solutions for Triaxial Galaxies
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 St\u7fackel 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 rst-order partial dierential equations in three variables. They were rst derived by Lynden{Bell in 1960, but have resisted solution by standard methods. Here we present the general solution by superposition of singular solutions