THE MOLECULAR H2 EMISSION AND THE STELLAR KINEMATICS IN THE NUCLEAR REGION OF THE SOMBRERO GALAXY

We analyze the molecular H-2 emission and the stellar kinematics in a data cube of the nuclear region of M104, the Sombrero galaxy, obtained with NIFS on the Gemini-north telescope. After a careful subtraction of the stellar continuum, the only emission line we detected in the data cube was H-2 lambda 21218. An analysis of this emission revealed the existence of a rotating molecular torus/disk, aproximately co-planar with a dusty structure detected by us in a previous work. We interpret these two structures as being associated with the same obscuring torus/disk. The kinematic maps provided by the Penalized Pixel Fitting method revealed that the stellar kinematics in the nuclear region of M104 appears to be the result of the superposition of a "cold" rotating disk and a "hot" bulge. Using a model of a thin eccentric disk, we reproduced the main properties of the maps of the stellar radial velocity and of the stellar velocity dispersion, especially within a distance of 0 ''.2 from the kinematic axis (in regions at larger distances, the limitations of a model of a thin rotating disk become more visible). The general behavior of the h(3) map, which is significantly noisier than the other maps, was also reproduced by our model (although the discrepancies, in this case, are considerably higher). With our model, we obtained a mass of (9.0 +/- 2.0) x 10(8)M(circle dot) for the supermassive black hole of M104, which is compatible, at 1 sigma or 2 sigma levels, with the values obtained by previous studies.