Gemini NIFS survey of feeding and feedback in nearbyActive Galaxies - III. Ionized versus warm molecular gasmasses and distributions

Abstract

We have used the Gemini Near-Infrared Integral Field Spectrograph (NIFS) in the J and K bands to map the distribution, excitation and kinematics of the ionized HII and warm molecular gas H$_2$, in the inner few 100 pc of 6 nearby active galaxies: NGC 788, Mrk 607, NGC 3227, NGC 3516, NGC 5506, NGC 5899. {For most galaxies, this is the first time that such maps have been obtained}. The ionized and H$_2$ gas show distinct kinematics: while the H$_2$ gas is mostly rotating in the galaxy plane with low velocity dispersion ($\sigma$), the ionized gas usually shows signatures of outflows associated with higher $\sigma$ values, most clearly seen in the [FeII] emission line. These two gas species also present distinct flux distributions: the H$_2$ is more uniformly spread over the whole galaxy plane, while the ionized gas is more concentrated around the nucleus and/or collimated along the ionization axis of its Active Galactic Nucleus (AGN), presenting a steeper gradient in the average surface mass density profile than the H$_2$ gas. The total HII masses cover the range $2\times10^5-2\times10^7$ M$_{\odot}$, with surface mass densities in the range 3-150 M$_{\odot}$ pc$^{-2}$, while for the warm H$_2$ the values are 10$^{3-4}$ times lower. We estimate that the available gas reservoir is at least $\approx$ 100 times more massive than needed to power the AGN. If this gas form new stars the star-formation rates, obtained from the Kennicutt-schmidt scalling relation, are in the range 1-260$\times$ 10$^{-3}$ M$_{\odot}$ yr$^{-1}$. But the gas will also - at least in part - be ejected in the form of the observed otflows.