We study molecular outflows in a sample of 45 local galaxies, both star forming and AGN, primarily by using CO data from the ALMA archive and from the literature. For a subsample we also compare the molecular outflow with the ionized and neutral atomic phases. We infer an empirical analytical function relating the outflow rate simultaneously to the SFR, L AGN , and galaxy stellar mass; this relation is much tighter than the relations with the individual quantities. The outflow kinetic power shows a larger scatter than in previous, more biased studies, spanning from 0.1 to 5 per cent of L AGN , while the momentum rate ranges from 1 to 30 times L AGN /c, indicating that these outflows can be both energy-driven, but with a broad range of coupling efficiencies with the ISM, and radiation pressure-driven. For about 10 per cent of the objects the outflow energetics significantly exceed the maximum theoretical values; we interpret these as "fossil outflows" resulting from activity of a past strong AGN, which has now faded. We estimate that, in the stellar mass range probed here (> 10 10 M ), less than 5 per cent of the outflowing gas escapes the galaxy. The molecular gas depletion time associated with the outflow can be as short as a few million years in powerful AGN, however, the total gas (H 2 +HI) depletion times are much longer. Altogether, our findings suggest that even AGN-driven outflows might be relatively ineffective in clearing galaxies of their entire gas content, although they are likely capable of clearing and quenching the central region.
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.
We study the ionization and kinematics of the ionized gas in the nuclear region of the barred Seyfert 2 galaxy NGC 5643 using MUSE integral field observations in the framework of the MAGNUM (Measuring Active Galactic Nuclei Under MUSE Microscope) survey. The data were used to identify regions with different ionization conditions and to map the gas density and the dust extinction. We find evidence for a double sided ionization cone, possibly collimated by a dusty structure surrounding the nucleus. At the center of the ionization cone, outflowing ionized gas is revealed as a blueshifted, asymmetric wing of the [OIII] emission line, up to projected velocity v 10 ∼ −450 km s −1 . The outflow is also seen as a diffuse, low luminosity radio and X-ray jet, with similar extension. The outflowing material points in the direction of two clumps characterized by prominent line emission with spectra typical of HII regions, located at the edge of the dust lane of the bar. We propose that the star formation in the clumps is due to 'positive feedback' induced by gas compression by the nuclear outflow, providing the first candidate for outflow induced star formation in a Seyfert-like radio quiet AGN. This suggests that positive feedback may be a relevant mechanism in shaping the black hole-host galaxy coevolution.
Context. Ionized outflows, revealed by broad asymmetric wings of the [O iii] λ5007 line, are commonly observed in active galactic nuclei (AGN) but the low intrinsic spatial resolution of the observations has generally prevented a detailed characterization of their properties. The MAGNUM survey aims at overcoming these limitations by focusing on the nearest AGN, including NGC 1365, a nearby Seyfert galaxy (D ∼ 17 Mpc), hosting a low-luminosity active nucleus (L bol ∼ 2 × 10 43 erg s −1 ). Aims. We want to obtain a detailed picture of the ionized gas in the central ∼5 kpc of NGC 1365 in terms of physical properties, kinematics, and ionization mechanisms. We also aim to characterize the warm ionized outflow as a function of distance from the nucleus and its relation with the nuclear X-ray wind. Methods. We employed optical integral-field spectroscopic observations from VLT/MUSE to investigate the warm ionized gas and Chandra ACIS-S X-ray data for the hot highly-ionized phase. We obtained flux, kinematic, and diagnostic maps of the optical emission lines, which we used to disentangle outflows from gravitational motions in the disk and measure the gas properties down to a spatial resolution of ∼70 pc. We then performed imaging spectroscopy on Chandra ACIS-S data guided by the matching with MUSE maps. Results. The [O iii] emission mostly traces a kpc-scale biconical outflow ionized by the AGN having velocities up to ∼200 km s −1 . Hα emission traces instead star formation in a circumnuclear ring and along the bar, where we detect non-circular streaming gas motions. Soft X-rays are predominantly due to thermal emission from the star-forming regions, but we manage to isolate the AGN photoionized component which nicely matches the [O iii] emission. The mass outflow rate of the extended ionized outflow is similar to that of the nuclear X-ray wind and then decreases with radius, implying that the outflow either slows down or that the AGN activity has recently increased. However, the hard X-ray emission from the circumnuclear ring suggests that star formation might in principle contribute to the outflow. The integrated mass outflow rate, kinetic energy rate, and outflow velocity are broadly consistent with the typical relations observed in more luminous AGN.
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