The MAGNUM survey: different gas properties in the outflowing and disc components in nearby active galaxies with MUSE

Abstract

We investigated the interstellar medium (ISM) properties of the disc and outflowing gas in the central regions of nine nearby Seyfert galaxies, all characterised by prominent conical or biconical outflows. These objects are part of the Measuring Active Galactic Nuclei Under MUSE Microscope (MAGNUM) survey, which aims to probe their physical conditions and ionisation mechanism by exploiting the unprecedented sensitivity of the Multi Unit Spectroscopic Explorer (MUSE), combined with its spatial and spectral coverage. Specifically, we studied the different properties of the gas in the disc and in the outflow with spatially and kinematically resolved maps by dividing the strongest emission lines in velocity bins. We associated the core of the lines with the disc, consistent with the stellar velocity, and the redshifted and the blueshifted wings with the outflow. We measured the reddening, density, ionisation parameter, and dominant ionisation source of the emitting gas for both components in each galaxy. We find that the outflowing gas is characterised by higher values of density and ionisation parameter than the disc, which presents a higher dust extinction. Moreover, we distinguish high-and low-ionisation regions across the portion of spatially resolved narrow-line region (NLR) traced by the outflowing gas. The high-ionisation regions characterised by the lowest [N ii]/Hα and [S ii]/Hα line ratios generally trace the innermost parts along the axis of the emitting cones where the [S iii]/[S ii] line ratio is enhanced, while the low-ionisation regions follow the cone edges and/or the regions perpendicular to the axis of the outflows, also characterised by a higher [O iii] velocity dispersion. A possible scenario to explain these features relies on the presence of two distinct populations of line emitting clouds: one is optically thin to the radiation and is characterised by the highest excitation, while the other is optically thick and is impinged by a filtered, and thus harder, radiation field which generates strong low-excitation lines. The highest values of [N ii]/Hα and [S ii]/Hα line ratios may be due to shocks and/or a hard filtered radiation field from the active galactic nucleus.

Ionized outflows in local luminous AGN: what are the real densities and outflow rates?

“…The median density for the inactive galaxies is 190 cm −3 , while that for the active galaxies is 350 cm −3 . A quantitatively similar result using the [S II] doublet was reported by Mingozzi et al (2019) who, for spatially resolved data of nine nearby AGN, reported that the mean density of 250 cm −3 in the outflows was higher than the mean of 130 cm −3 for the circumnuclear discs.…”

Physics of ULIRGs with MUSE and ALMA: The PUMA project

“…The MUSE data presented here also provide a complementary view of outflow phenomena with respect to other MUSE surveys, for instance targeting local Seyfert galaxies (e.g. MAGNUM, Mingozzi et al 2019;CARS, Husemann et al 2019), whose outflows would likely originate from AGN, or galaxies with prominent nuclear rings and bars (TIMER, Gadotti et al 2019), whose outflows would probably originate from AGN and/or SB activity triggered by secular processes.…”

GASP – XIX. AGN and their outflows at the centre of jellyfish galaxies

“…Different models were presented to reproduce coronal lines in AGN. Mingozzi et al (2019) reported the presence of Fe coronal lines in a sample of AGN with outflows, observed with MUSE: they attributed them to the inner, optically thin and highly ionized regions of the outflows. Korista & Ferland (1989) attributed them to a low-density (ne ∼ 1 cm −3 ) ISM heated by the AGN radiation, in a region whose size is similar or larger than the NLR (∼ 1-2 kpc).…”