We report R \sim 3000 Very Large Telescope ISAAC K-band spectroscopy of the nuclei ( i.e .
central 100–300 pc ) of nine galaxies hosting an active galactic nucleus .
For five of these we also present spectra of the circumnuclear region out to 1 kpc .
We have measured a number of molecular hydrogen lines in the \nu = 1 - 0 , 2 - 1 , and 3 - 2 vibrational transitions , as well as the Br \gamma and He i recombination lines , and the Na i stellar absorption feature .
Although only three of the galaxies are classified as type 1 Seyferts in the literature , broad Br \gamma ( FWHM \gtrsim 1000 km s ^ { -1 } ) is seen in seven of the objects .
The \nu = 1 - 0 emission appears thermalised at temperatures T \sim 1000 K. However , the \nu = 2 - 1 and \nu = 3 - 2 emission show evidence of being radiatively excited by far-ultraviolet photons .
The photo-dissociation region models that fit the data best are , as for the ultraluminous infrared galaxies in ( 13 ) , those for which the H _ { 2 } emission arises in dense clouds illuminated by intense FUV radiation .
The Na i stellar absorption line is clearly seen in six of the nuclear spectra of these AGN , indicating the presence of a significant population of late type stars .
It is possible that these stars are a result of the same episode of star formation that gave rise to the stars heating the PDRs .
It seems unlikely that the AGN is the dominant source of excitation for the near infrared H _ { 2 } emission : in two of the nuclear spectra H _ { 2 } was not detected at all , and in general we find no evidence of suppression of the 2-1 S ( 3 ) line , which may occur in X-ray irradiated gas .
Our data do not reveal any significant difference between the nuclear and circumnuclear line ratios , suggesting that the physical conditions of the dominant excitation mechanism are similar both near the AGN and in the larger scale environment around it , and that star formation is an important process even in the central 100 pc acround AGN .