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Register a new userQuantifying Feedback from Narrow Line Region Outflows in Nearby Active Galaxies. II. Spatially Resolved Mass Outflow Rates for the QSO2 Markarian 34
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We present spatially resolved mass outflow rate measurements ($dot M_{out}$) for the narrow line region of Markarian 34, the nearest Compton-thick type 2 quasar (QSO2). Spectra obtained with the Hubble Space Telescope and at Apache Point Observatory reveal complex kinematics, with distinct signatures of outflow and rotation within 2 kpc of the nucleus. Using multi-component photoionization models, we find that the outflow contains a total ionized gas mass of $M approx 1.6 times 10^6 M_{odot}$. Combining this with the kinematics yields a peak outflow rate of $dot M_{out} approx 2.0 pm 0.4~M_{odot}$ yr$^{-1}$ at a distance of 470 pc from the nucleus, with a spatially integrated kinetic energy of $E approx 1.4 times 10^{55}$ erg. These outflows are more energetic than those observed in Mrk 573 and NGC 4151, supporting a correlation between luminosity and outflow strength even though they have similar peak outflow rates. The mix of rotational and outflowing components suggests that spatially resolved observations are required to determine accurate outflow parameters in systems with complex kinematics. (See appended erratum for updated values.)
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Outflows of ionized gas driven by active galactic nuclei (AGN) may significantly impact the evolution of their host galaxies. However, determining the energetics of these outflows is difficult with spatially unresolved observations that are subject to strong global selection effects. We present part of an ongoing study using Hubble Space Telescope (HST) and Apache Point Observatory (APO) spectroscopy and imaging to derive spatially-resolved mass outflow rates and energetics for narrow line region (NLR) outflows in nearby AGN that are based on multi-component photoionization models to account for spatial variations in the gas ionization, density, abundances, and dust content. This expanded analysis adds Mrk 3, Mrk 78, and NGC 1068, doubling the sample in Revalski (2019). We find that the outflows contain total ionized gas masses of $M approx 10^{5.5} - 10^{7.5}$ $M_{odot}$ and reach peak velocities of $v approx 800 - 2000$ km s$^{-1}$. The outflows reach maximum mass outflow rates of $dot M_{out} approx 3 - 12$ $M_{odot}$ yr$^{-1}$ and encompass total kinetic energies of $E approx 10^{54} - 10^{56}$ erg. The outflows extend to radial distances of $r approx 0.1 - 3$ kpc from the nucleus, with the gas masses, outflow energetics, and radial extents positively correlated with AGN luminosity. The outflow rates are consistent with in-situ ionization and acceleration where gas is radiatively driven at multiple radii. These radial variations indicate that spatially-resolved observations are essential for localizing AGN feedback and determining the most accurate outflow parameters.
We have analyzed HST spectroscopy of 24 nearby AGNs to investigate spatially-resolved gas kinematics in the Narrow Line Region (NLR). These observations effectively isolate the nuclear line profiles on less than 100 pc scales and are used to investigate the origin of the substantial scatter between the widths of strong NLR lines and the stellar velocity dispersion sigma_* of the host galaxy, a quantity which relates with substantially less scatter to the mass of the central, supermassive black hole, and more generally characterize variations in the NLR velocity field with radius. We find that line widths measured with STIS at a range of spatial scales systematically underestimate both sigma_* and the line width measured from ground-based observations, although they do have comparably large scatter to the relation between ground-based NLR line width and sigma_*. There are no obvious trends in the residuals when compared with a range of host galaxy and nuclear properties. The widths and asymmetries of [OIII] 5007 and [SII] 6716, 6731 as a function of radius exhibit a wide range of behavior. Some of the most common phenomena are substantial width increases from the STIS to the large-scale, ground-based aperture and almost no change in line profile between the unresolved nuclear spectrum and ground-based measurements. We identify asymmetries in a surprisingly large fraction of low-ionization [SII] line profiles and several examples of substantial red asymmetries in both [OIII] and [SII]. These results underscore the complexity of the circumnuclear material that constitutes the NLR and suggest that the scatter in the NLR width and sigma_* correlation can not be substantially reduced with a simple set of empirical relations.
We have examined the physical conditions in the narrow-line region (NLR) of the Seyfert 2 galaxy Markarian 3, using long-slit spectra obtained with the Hubble Space Telescope/Space Telescope Imaging Spectrograph and photoionization models. We find three components of photoionized gas in the NLR. Two of these components, characterized by emission lines such as [NeV] 3426 and [OIII] 5007, lie within the envelope of the bi-conical region described in our previous kinematic study. A component of lower ionization gas, in which lines such as [OII] 3727 arise, is found to lie outside the bi-cone. Each of these components is irradiated by a power-law continuum which is attenuated by intervening gas, presumably closer to the central source. The radiation incident upon the low ionization gas, external to the bi-cone, is much more heavily absorbed. These absorbers are similar to the intrinsic UV and X-ray absorbers detected in many Seyfert 1 galaxies, which suggests that the collimation of the ionizing radiation occurs in a circumnuclear wind, rather than a thick, molecular torus. We estimate the mass for the observed NLR emitting gas to be 2 million solar-masses. It is likely that Markarian 3 acquired this gas through an on-going interaction with the spiral galaxy UGC 3422.
We present optical integral field spectroscopy for five $z<0.062$ narrow-line Seyfert 1 galaxies (NLS1s) host galaxies, probing their host galaxies at $gtrsim 2-3$ kpc scales. Emission lines in the nuclear AGN spectra and the large-scale host galaxy are analyzed separately, based on an AGN-host decomposition technique. The host galaxy gas kinematics indicates large-scale gas rotation in all five sources. At the probed scales of $gtrsim 2-3$ kpc, the host galaxy gas is found to be predominantly ionized by star formation without any evidence of a strong AGN contribution. None of the five objects shows specific star formation rates exceeding the main sequence of low-redshift star forming galaxies. The specific star formation rates for MCG-05-01-013 and WPVS 007 are roughly consistent with the main sequence, while ESO 399-IG20, MS 22549-3712, and TON S180 show lower specific star formation rates, intermediate to the main sequence and red quiescent galaxies. The host galaxy metallicities, derived for the two sources with sufficient data quality (ESO 399-IG20 and MCG-05-01-013), indicate central oxygen abundances just below the low-redshift mass-metallicity relation. Based on this initial case study, we outline a comparison of AGN and host galaxy parameters as a starting point for future extended NLS1 studies with similar methods.
Although studying outflows in the host galaxies of AGN have become the forefront of extra-galactic astronomy in recent years, estimating the energy associated with these outflows have been a major challenge. Determination of the energy associated with an outflow often involves an assumption of uniform density in the NLR, which span a wide range in literature leading to large systematic uncertainties in energy estimation. In this paper, we present electron density maps for a sample of outflowing and non-outflowing Seyfert galaxies at z<0.02 drawn from the S7 survey and understand the origin and values of the observed density structures to reduce the systematic uncertainties in outflow energy estimation. We use the ratio of the [SII]6716,6731 emission lines to derive spatially resolved electron densities (<50-2000 cm$^{-3}$). Using optical IFU observations, we are able to measure densities across the central 2-5 kpc of the selected AGN host galaxies. We compare the density maps with the positions of the HII regions derived from the narrow H$alpha$ component, ionization maps from [OIII], and spatially resolved BPT diagrams, to infer the origin of the observed density structures. We also use the electron density maps to construct density profiles as a function of distance from the central AGN. We find a spatial correlation between the sites of high star formation and high electron density for targets without an active ionized outflow. The non-outflowing targets also show an exponential drop in the electron density as a function of distance from the center, with a mean exponential index of ~0.15. The correlation between the star forming sites and electron density ceases for targets with an outflow. The density within the outflowing medium is not uniform and shows both low and high density sites, most likely due to the presence of shocks and highly turbulent medium.
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