Dynamique des galaxies de type précoce:observations 3D et modélisations

Answers to key questions regarding scenarios of galaxy formation and evolution require extensive morphological, kinematic and stellar population studies along the Hubble sequence, to which integral field spectroscopy (IFS) can greatly benefit. In this context, the subject of this thesis is the study of early-type galaxy dynamics, more specifically tackled with IFS.<br /><br />At first, I present the international project SAURON, which aims at observing a sample of ~ 80 early-type galaxies with a dedicated integral wide-field spectrograph. I describe in detail the specific reduction process applied to datacubes from this instrument, as well as methods implemented to extract the line-of-sight velocity distribution.<br /><br />Various applications of IFS to the study of galactic dynamics are then presented. At high spatial resolution (0''5), observations of the double nucleus of M31 with OASIS exhibits its outstanding morphological and kinematic complexity. On a larger scale (30 x 40 arcsec2), first results from SAURON could be used for a new characterization of galactic kinematics from the study of their bidimensional velocity field. Last, I present first elements of a dynamical Schwarzschild's modelization of galaxy NGC 3377, based upon fully complementary data from OASIS and SAURON.<br /><br />The last section of this thesis deals with the orbit, basic building block of the galactic dynamics, the precise computation of dynamical properties of which remains a major difficulty in the application of Schwarzschild's method. To deal with this issue, we developed a regular orbit probing tool based on a semi-analytic reconstruction of the orbital torus using concepts from spectral dynamics.