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Register a new userIonized outflows in local luminous AGN: what are the real densities and outflow rates?
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We report on the determination of electron densities, and their impact on the outflow masses and rates, measured in the central few hundred parsecs of 11 local luminous active galaxies. We show that the peak of the integrated line emission in the AGN is significantly offset from the systemic velocity as traced by the stellar absorption features, indicating that the profiles are dominated by outflow. In contrast, matched inactive galaxies are characterised by a systemic peak and weaker outflow wing. We present three independent estimates of the electron density in these AGN, discussing the merits of the different methods. The electron density derived from the [SII] doublet is significantly lower than than that found with a method developed in the last decade using auroral and transauroral lines, as well as a recently introduced method based on the ionization parameter. The reason is that, for gas photoionized by an AGN, much of the [SII] emission arises in an extended partially ionized zone where the implicit assumption that the electron density traces the hydrogen density is invalid. We propose ways to deal with this situation and we derive the associated outflow rates for ionized gas, which are in the range 0.001--0.5 M$_{odot}$yr$^{-1}$ for our AGN sample. We compare these outflow rates to the relation between $dot{M}_{out}$ and $L_{AGN}$ in the literature, and argue that it may need to be modified and rescaled towards lower mass outflow rates.
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Low excitation radio galaxies (LERGs) are weakly accreting active galactic nuclei (AGN) believed to be fuelled by radiatively inefficient accretion processes. Despite this, recent works have shown evidence for ionized and neutral hydrogen gas outflows in these galaxies. To investigate the potential drivers of such outflows we select a sample of 802 LERGs using the Best & Heckman (2012) catalogue of radio galaxies. By modelling the [O III] $lambda 5007$ profile in Sloan Digital Sky Survey spectra of a sample of 802 LERGs, we determine that the ionized outflows are present in $sim 1.5%$ of the population. Using $1.4~text{GHz}$ imaging from the Faint Images of the Radio Sky at Twenty Centimeters survey we analyze the radio morphology of LERGs with outflows and find these to be consistent with the parent LERG population. However, we note that unlike the majority of the LERG population, those LERGs showing outflows have Eddington scaled accretion rates close to $1%$. This is indicative that ionized outflows in LERGs are driven by the radiation pressure from the accretion disk of the AGN rather than the radio jets. We report specific star formation rates in the range of $10^{-12} < text{sSFR} < 10^{-9}~text{yr}^{-1}$. Moreover, we observe higher mass outflow rates of $7-150~M_{odot}~text{yr}^{-1}$ for these LERGs than luminous quasars for a given bolometric luminosity, which could possibly be due to the radio source in LERGs boosting the mass-loading. This scenario could indicate that these outflows could potentially drive feedback in LERGs.
Galactic outflows are known to consist of several gas phases, however, so far the connection between these multiple phases has been investigated little and only in a few objects. In this paper, we analyse MUSE/VLT data of 26 local (U)LIRGs and study their ionised and neutral atomic phases. We also include objects from the literature to obtain a total sample of 31 galaxies with spatially resolved multi-phase outflow information. We find that the ionized phase of the outflows has on average an electron density three times higher than the disc ($n_{rm e, disc}$ $sim$ 145 cm$^{-3}$ vs $n_{rm e, outflow}$ $sim$ 500 cm$^{-3}$), suggesting that cloud compression in the outflow is more important that cloud dissipation. We find that the difference in extinction between outflow and disc correlates with the outflow gas mass. Together with the analysis of the outflow velocities, this suggests that at least some of the outflows are associated with the ejection of dusty clouds from the disc. This may support models where radiation pressure on dust contributes to driving galactic outflows. The presence of dust in outflows is relevant for potential formation of molecules inside them. We combine our data with millimetre data to investigate the molecular phase. We find that the molecular phase accounts for more than 60 $%$ of the total mass outflow rate in most objects and this fraction is higher in AGN-dominated systems. The neutral atomic phase contributes of the order of 10 $%$, while the ionized phase is negligible. The ionized-to-molecular mass outflow rate declines slightly with AGN luminosity, although with a large scatter.
Luminous infrared galaxies (LIRGs) are enshrouded by a large amount of dust, produced by their active star formation, and it is difficult to measure their activity in the optical wavelength. We have carried out Pa$alpha$ narrow-band imaging observations of 38 nearby star-forming galaxies including 33 LIRGs listed in $IRAS$ RBGS catalog with the Atacama Near InfraRed camera (ANIR) on the University of Tokyo Atacama Observatory (TAO) 1.0 m telescope (miniTAO). Star formation rates (SFRs) estimated from the Pa$alpha$ fluxes, corrected for dust extinction using the Balmer Decrement Method (typically $A_V$ $sim$ 4.3 mag), show a good correlation with those from the bolometric infrared luminosity of $IRAS$ data within a scatter of 0.27 dex. This suggests that the correction of dust extinction for Pa$alpha$ flux is sufficient in our sample. We measure the physical sizes and the surface density of infrared luminosities ($Sigma_{L(mathrm{IR})}$) and $SFR$ ($Sigma_{SFR}$) of star-forming region for individual galaxies, and find that most of the galaxies follow a sequence of local ultra luminous or luminous infrared galaxies (U/LIRGs) on the $L(mathrm{IR})$-$Sigma_{L(mathrm{IR})}$ and $SFR$-$Sigma_{SFR}$ plane. We confirm that a transition of the sequence from normal galaxies to U/LIRGs is seen at $L(mathrm{IR})=8times10^{10}$ $L_{odot}$. Also, we find that there is a large scatter in physical size, different from those of normal galaxies or ULIRGs. Considering the fact that most of U/LIRGs are merging or interacting galaxies, this scatter may be caused by strong external factors or differences of their merging stage.
Luminous Compact Blue Galaxies (LCBGs) are common at z~1, contributing significantly to the total star formation rate density. By z~0, they are a factor of ten rarer. While we know that LCBGs evolve rapidly, we do not know what drives their evolution nor into what types of galaxies they evolve. We present the results of a single-dish HI survey of local LCBGs undertaken to address these questions. Our results indicate that LCBGs have M(HI) and M(DYN) consistent with low-mass spirals, but typically exhaust their gas reservoirs in less than 2 Gyr. Overall, the properties of LCBGs are consistent with them evolving into high-mass dwarf elliptical or dwarf irregular galaxies or low-mass, late-type spiral galaxies.
We analyse optical datacubes of the inner kiloparsec of 30 local ($zle0.02$) active galactic nuclei (AGN) hosts that our research group, AGNIFS, has collected over the past decade via observations with the integral field units of the Gemini Multi-Object Spectrographs. Spatial resolutions range between $50~{rm pc}$ and $300~{rm pc}$ and spectral coverage is from $4800~mathring{A}$ or $5600~mathring{A}$ to $7000~mathring{A}$, at velocity resolutions of $approx 50~{rm km~s^{-1}}$. We derive maps of the gas excitation and kinematics, determine the AGN ionisation axis -- which has random orientation relative to the galaxy, and the kinematic major axes of the emitting gas. We find that rotation dominates the gas kinematics in most cases, but is disturbed by the presence of inflows and outflows. Outflows have been found in 21 nuclei, usually along the ionisation axis. The gas velocity dispersion is traced by $W_{80}$ (velocity width encompassing 80 per cent of the line flux), adopted as a tracer of outflows. In 7 sources $W_{80}$ is enhanced perpendicularly to the ionisation axis, indicating lateral expansion of the outflow. We have estimated mass-outflow rates $dot{M}$ and powers $dot{E}$, finding median values of $log,[dot{M}/({rm,M_odot,yr^{-1}})]=-2.1_{-1.0}^{+1.6}$ and $log,[dot{E}/({rm,erg,s^{-1}})]=38.5_{-0.9}^{+1.8}$, respectively. Both quantities show a mild correlation with the AGN luminosity ($L_{rm AGN}$). $dot{E}$ is of the order of 0.01 $L_{rm AGN}$ for 4 sources, but much lower for the majority (9) of the sources, with a median value of $log,[dot{E}/L_{rm AGN}]=-5.34_{-0.9}^{+3.2}$ indicating that typical outflows in the local Universe are unlikely to significantly impact their host galaxy evolution.
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