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We present the first results of an analysis of the properties of themolecular gas in the nuclear regions (r < 300 pc) of a sample of six nearbygalaxies, based on new high spatial resolution observations obtained in theK-band with the near-infrared integral field spectrograph SINFONI at the VeryLarge Telescope. We derive two-dimensional distributions of the warm molecularand ionized gas from the H2, Br_gamma and HeI emission lines present in thespectra of the galaxies. We find a range of morphologies, including bar- andring-like distributions and either centrally peaked or off-centre emission. Themorphologies of the molecular and the ionized gas are not necessarilycoincident. The observed emission-line ratios point towards thermal processesas the principal mechanism responsible for the H2 excitation in the nuclear andcircumnuclear regions of the galaxies, independently of the presence of anactive nucleus. We find that a rescaling of the H2 2.12 microns emission-lineluminosity by a factor beta~1200 gives a good estimate (within a factor of 2)of the total (cold) molecular gas mass. The galaxies of the sample containlarge quantities of molecular gas in their centres, with total masses in the ~105 - 108 Msol range. Never the less, these masses correspond to less than 3per cent of the stellar masses derived for the galaxies in these regions,indicating that the presence of gas should not affect black hole mass estimatesbased on the dynamical modelling of the stars. The high-spatial resolutionprovided by the SINFONI data allowed us to resolve a circumnuclear ring (with aradius of ~270 pc) in the galaxy NGC 4536. The measured values of the Br_gammaequivalent width and the HeI/Br_gamma emission-line ratio suggests that burstsof star formation occurred throughout this ring as recently as 6.5 Myr ago.

Molecular gas in the centre of nearby galaxies from VLT/SINFONI integral field spectroscopy - I. Morphology and mass inventory