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Abstract:
We use the Gemini NIFS instrument to map the H<SUB>2</SUB>2.1218μm and Brγ flux distributions in the inner 0.04–2 kpc of a sample of 36 nearby active galaxies (0.001 ≲ z ≲ 0.056) at spatial resolutions from 4 to 250 pc. We find extended emission in 34 galaxies. In ∼55 per cent of them, the emission in both lines is most extended along the galaxy major axis, while in the other 45 per cent the extent follows a distinct orientation. The emission of H<SUB>2</SUB> is less concentrated than that of Brγ, presenting a radius that contains half of the flux 60 per cent greater, on average. The H<SUB>2</SUB> emission is driven by thermal processes – X-ray heating and shocks – at most locations for all galaxies, where 0.4<H<SUB>2</SUB>/Brγ<6. For regions where H<SUB>2</SUB>/Brγ > 6 (seen in 40 per cent of the galaxies), shocks are the main H<SUB>2</SUB> excitation mechanism, while in regions with H<SUB>2</SUB>/Brγ < 0.4 (25 per cent of the sample) the H<SUB>2</SUB> emission is produced by fluorescence. The only difference we found between type 1 and type 2 active galactic nucleus (AGN) was in the nuclear emission-line equivalent widths that are smaller in type 1 than in type 2 due to a larger contribution to the continuum from the hot dusty torus in the former. The gas masses in the inner 125 pc radius are in the range 10<sup>1</sup>−10<sup>4</sup> M<sub>⊙</sub> for the hot H<sub>2</sub> and 10<sup>3</sup>−10<sup>6</sup> M<sub>⊙</sub> for the ionized gas and would be enough to power the AGN in our sample for 10<sup>5</sup>−10<sup>8</sup> yr at their current accretion rates.
