2021/04/07 by R. A. Riffel, T. Storchi-Bergmann, R. Riffel +13 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stab998
21 pages, accepted for publication in MNRAS
arxiv created 2021/04/07 · arxiv updated 2021/04/21
We use the Gemini NIFS instrument to map the H2 2.1218μm and Brγ flux distributions in the inner 0.04-2 kpc of a sample of 36 nearby active galaxies (0.001\lesssim z\lesssim0.056) at spatial resolutions from 4 to 250 pc. We find extended emission in 34 galaxies. In ∼55% of them, the emission in both lines is most extended along the galaxy major axis, while in the other 45% the extent follows a distinct orientation. The emission of H2 is less concentrated than that of Brγ, presenting a radius that contains half of the flux 60% greater, on average. The H2 emission is driven by thermal processes - X-ray heating and shocks - at most locations for all galaxies, where 0.4<H2/Brγ<6. For regions where H2/Brγ>6 (seen in 40% of the galaxies), shocks are the main H2 excitation mechanism, while in regions with H2/Brγ<0.4 (25% of the sample) the H2 emission is produced by fluorescence. The only difference we found between type 1 and type 2 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 101-104 M_\odot for the hot H2 and 103-106 M_\odot for the ionised gas and would be enough to power the AGN in our sample for 105-108 yr at their current accretion rates.