arXiv subjects

Rebecca McElroy

Publications and source records attributed to Rebecca McElroy.

18 recordsLinked to original sources

arXiv2026

The PHANGS-Hα survey. Ground-based narrow-band imaging of nearby star-forming galaxies

We present PHANGS-Hα, a narrow-band imaging survey that maps Hα emission over a sample of 65 nearby massive star-forming galaxies. The data were obtained using the MPG-ESO 2.2-meter telescope at La Silla and the du Pont 2.5-meter telescope at Las Campanas Observatory, in the framework of the multi-wavelength cloud-scale (50-100 pc) resolution mapping of molecular gas and star formation conducted by the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) collaboration. PHANGS-Hα complements the already published PHANGS-ALMA, PHANGS-MUSE, PHANGS-HST, and PHANGS-JWST surveys, providing an anchor point for the photometric and astrometric calibration of these datasets, as well as samples of H ii regions, and star formation rate maps for the bulk of the PHANGS sample. We present observations, data processing, and calibration of the PHANGS-Hα dataset, as well as the procedures used to derive emission-line fluxes from narrow-band imaging. A subset of galaxies with available spectroscopic Ha mapping from the PHANGS-MUSE survey allows for a detailed comparison with the narrow-band photometry presented here. This informs a series of best practices for the processing of narrow-band Hα imaging that we apply to the full dataset.

astro-ph.GA↗

arXiv2025

A century of change: new changing-look event in Mrk 1018's past

We investigate the long-term variability of the known Changing Look Active Galactic Nuclei (CL AGN) Mrk 1018, whose second change we discovered as part of the Close AGN Reference Survey (CARS). Collating over a hundred years worth of photometry from scanned photographic plates and five modern surveys we find a historic outburst between ~1935-1960, with variation in Johnson B magnitude of ~0.8 that is consistent with Mrk 1018's brightness before and after its latest changing look event in the early 2010s. Using the combined modern and historic data, a Generalised Lomb-Scargle suggests broad feature with P = 29-47 years. Its width and stability across tests, as well as the turn-on speed and bright phase duration of the historic event suggests a timescale associated with long-term modulation, such as via rapid flickering in the accretion rate caused by the Chaotic Cold Accretion model rather than a strictly periodic CL mechanism driving changes in Mrk 1018. We also use the modern photometry to constrain Mrk 1018's latest turn-off duration to less than ~1.9 years, providing further support for a CL mechanism with rapid transition timescales, such as a changing mode of accretion.

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arXiv2025

The Close AGN Reference Survey (CARS): A comparison between sub-mm and optical AGN diagnostic diagrams

The $L_{\rm IR}-L_{\rm HCN}$ relation suggests that there is a tight connection between dense gas and star formation. We use data from the Close AGN Reference Survey (CARS) to investigate the dense gas - star formation relation in AGN hosting galaxies, and the use of dense gas as an active galactic nuclei (AGN) diagnostic. Our sample contains five Type-1 (unobscured) AGN that were observed with the Atacama Large Millimeter/submillimeter Array (ALMA) with the aim to detect HCN(4-3), HCO$^+$(4-3) and CS(7-6). We detect the dense gas emission required for this analysis in 3 of the 5 targets. We find that despite the potential impact from the AGN on the line fluxes of these sources, they still follow the $L_{\rm IR}-L_{\rm HCN}$ relation. We then go on to test claims that the HCN/HCO+ and HCN/CS line ratios can be used as a tool to classify AGN in the sub-mm HCN diagram. We produce the classic ionised emission-line ratio diagnostics (the so-called BPT diagrams), using available CARS data from the Multi Unit Spectroscopic Explorer (MUSE). We then compare the BPT classification with the sub-mm classification made using the dense gas tracers. Where it was possible to complete the analysis we find general agreement between optical and sub-mm classified gas excitation mechanisms. This suggests that AGN can contribute to the excitation of both the low density gas in the warm ionised medium and the high density gas in molecular clouds simultaneously, perhaps through X-ray, cosmic ray or shock heating mechanisms.

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arXiv2022

The Close AGN Reference Survey (CARS). A parsec scale multi-phase outflow in the super-Eddington NLS1 Mrk 1044

The interaction between Active Galactic Nuclei (AGN) and their host galaxies is scarcely resolved. Narrow-line Seyfert 1 (NLS1) galaxies are believed to represent AGN at early stages of their evolution and allow to observe AGN feeding and feedback processes at high accretion rates. We apply a spectroastrometric analysis to VLT MUSE NFM-AO observations of Mrk 1044, a nearby super-Eddington accreting NLS1. This allows us to map two ionised gas outflows traced by [O$\,$III] which have velocities of $-560\pm20\,{\rm km\:s}^{-1}$ and $-144 \pm 5 \,{\rm km\:s}^{-1}$. Both outflows are spatially unresolved and located close to the galaxy nucleus ($<1\,{\rm pc}$). They have gas densities higher than $10^5\,{\rm cm}^{-3}$, which implies that the BPT diagnostic cannot be used to constrain the underlying ionisation mechanism. We explore whether an expanding shell model can describe the velocity structure of Mrk 1044's unresolved multi-phase outflow. A kinematic analysis suggests that significant turbulence may be present in the ISM around the nucleus, which may lead to a condensation rain, potentially explaining the efficient feeding of Mrk 1044's AGN. We identify an additional ionised gas outflowing component that is spatially resolved. It has a velocity of $-211 \pm 22 \,{\rm km\:s}^{-1}$ and a projected size of $4.6 \pm 0.6 \,{\rm pc}$. Within the innermost 0.5" (160$\,{\rm pc}$) around the nucleus we detect modest star formation hidden by the beam-smeared emission from the outflow, which suggests that Mrk 1044's AGN phase set on recently. We estimate that the multi-phase outflow has been launched $<10^4 \,{\rm yrs}$ ago. It carries enough mass and energy to impact the host galaxy star formation on different spatial scales, highlighting the complexity of the AGN feeding and feedback cycle in its early stages.

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arXiv2022

Environmental dependence of the molecular cloud lifecycle in 54 main sequence galaxies

The processes of star formation and feedback, regulating the cycle of matter between gas and stars on the scales of giant molecular clouds (GMCs; $\sim$100pc), play a major role in governing galaxy evolution. Measuring the time-scales of GMC evolution is important to identify and characterise the specific physical mechanisms that drive this transition. By applying a robust statistical method to high-resolution CO and narrow-band H$α$ imaging from the PHANGS survey, we systematically measure the evolutionary timeline from molecular clouds to exposed young stellar regions on GMC scales, across the discs of an unprecedented sample of 54 star-forming main-sequence galaxies (excluding their unresolved centres). We find that clouds live for about $1{-}3$ GMC turbulence crossing times ($5{-}30$Myr) and are efficiently dispersed by stellar feedback within $1{-}5$Myr once the star-forming region becomes partially exposed, resulting in integrated star formation efficiencies of $1{-}8$%. These ranges reflect physical galaxy-to-galaxy variation. In order to evaluate whether galactic environment influences GMC evolution, we correlate our measurements with average properties of the GMCs and their local galactic environment. We find several strong correlations that can be physically understood, revealing a quantitative link between galactic-scale environmental properties and the small-scale GMC evolution. Notably, the measured CO-visible cloud lifetimes become shorter with decreasing galaxy mass, mostly due to the increasing presence of CO-dark molecular gas in such environment. Our results represent a first step towards a comprehensive picture of cloud assembly and dispersal, which requires further extension and refinement with tracers of the atomic gas, dust, and deeply-embedded stars.

astro-ph.GA↗

arXiv2022

The observability of galaxy merger signatures in nearby gas-rich spirals

Galaxy mergers are crucial to understanding galaxy evolution, therefore we must determine their observational signatures to select them from large IFU galaxy samples such as MUSE and SAMI. We employ 24 high-resolution idealised hydrodynamical galaxy merger simulations based on the "Feedback In Realistic Environment" (FIRE-2) model to determine the observability of mergers to various configurations and stages using synthetic images and velocity maps. Our mergers cover a range of orbital configurations at fixed 1:2.5 stellar mass ratio for two gas rich spirals at low redshift. Morphological and kinematic asymmetries are computed for synthetic images and velocity maps spanning each interaction. We divide the interaction sequence into three: (1) the pair phase; (2) the merging phase; and (3) the post-coalescence phase. We correctly identify mergers between first pericentre passage and 500 Myr after coalescence using kinematic asymmetry with 66% completeness, depending upon merger phase and the field-of-view of the observation. We detect fewer mergers in the pair phase (40%) and many more in the merging and post-coalescence phases (97%). We find that merger detectability decreases with field-of-view, except in retrograde mergers, where centrally concentrated asymmetric kinematic features enhances their detectability. Using a cut-off derived from a combination of photometric and kinematic asymmetry, we increase these detections to 89% overall, 79% in pairs, and close to 100% in the merging and post-coalescent phases. By using this combined asymmetry cut-off we mitigate some of the effects caused by smaller fields-of-view subtended by massively multiplexed integral field spectroscopy programmes.

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arXiv2022

The PHANGS-MUSE survey -- Probing the chemo-dynamical evolution of disc galaxies

We present the PHANGS-MUSE survey, a programme using the MUSE IFS at the ESO VLT to map 19 massive $(9.4 < \log(M_{*}/M_\odot) < 11.0)$ nearby (D < 20 Mpc) star-forming disc galaxies. The survey consists of 168 MUSE pointings (1'x1' each), a total of nearly 15 Million spectra, covering ~1.5 Million independent spectra. PHANGS-MUSE provides the first IFS view of star formation across different local environments (including galaxy centres, bars, spiral arms) in external galaxies at a median resolution of 50~pc, better than the mean inter-cloud distance in the ionised interstellar medium. This `cloud-scale' resolution allows detailed demographics and characterisations of HII regions and other ionised nebulae. PHANGS-MUSE further delivers a unique view on the associated gas and stellar kinematics, and provides constraints on the star formation history. The PHANGS-MUSE survey is complemented by dedicated ALMA CO(2-1) and multi-band HST observations, therefore allowing us to probe the key stages of the star formation process from molecular clouds to HII regions and star clusters. This paper describes the scientific motivation, sample selection, observational strategy, data reduction and analysis process of the PHANGS-MUSE survey. We present our bespoke automated data-reduction framework, which is built on the reduction recipes provided by ESO, but additionally allows for mosaicking and homogenisation of the point spread function. We further present a detailed quality assessment and a brief illustration of the potential scientific applications of the large set of PHANGS-MUSE data products generated by our data analysis framework. The data cubes and analysis data products described in this paper represent the basis for the first PHANGS-MUSE public data release and are available in the ESO archive and via the Canadian Astronomy Data Centre.

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arXiv2022

The Gas-Star Formation Cycle in Nearby Star-forming Galaxies II. Resolved Distributions of CO and H$α$ Emission for 49 PHANGS Galaxies

The relative distribution of molecular gas and star formation in galaxies gives insight into the physical processes and timescales of the cycle between gas and stars. In this work, we track the relative spatial configuration of CO and H$α$ emission at high resolution in each of our galaxy targets, and use these measurements to quantify the distributions of regions in different evolutionary stages of star formation: from molecular gas without star formation traced by H$α$ to star-forming gas, and to HII regions. The large sample, drawn from the Physics at High Angular resolution in Nearby GalaxieS ALMA and narrowband H$α$ (PHANGS-ALMA and PHANGS-H$α$) surveys, spans a wide range of stellar mass and morphological types, allowing us to investigate the dependencies of the gas-star formation cycle on global galaxy properties. At a resolution of 150 pc, the incidence of regions in different stages shows a dependence on stellar mass and Hubble type of galaxies over the radial range probed. Massive and/or earlier-type galaxies exhibit a significant reservoir of molecular gas without star formation traced by H$α$, while lower-mass galaxies harbor substantial HII regions that may have dispersed their birth clouds or formed from low-mass, more isolated clouds. Galactic structures add a further layer of complexity to relative distribution of CO and H$α$ emission. Trends between galaxy properties and distributions of gas traced by CO and H$α$ are visible only when the observed spatial scale is $\ll$ 500 pc, reflecting the critical resolution requirement to distinguish stages of star formation process.

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arXiv2021

PHANGS-MUSE: the HII region luminosity function of local star-forming galaxies

We use an unprecedented sample of about 23,000 HII regions detected at an average physical resolution of 67pc in the PHANGS-MUSE sample to study the extragalactic HII region Ha luminosity function (LF). Our observations probe the star-forming disk of 19 nearby spiral galaxies with low inclination and located close to the star formation main sequence at z=0. The mean LF slope $α$ in our sample is =1.73 with a $σ$ of 0.15. We find that $α$ decreases with the galaxy's star formation rate surface density and argue that this is driven by an enhanced clustering of young stars at high gas surface densities. Looking at the HII regions within single galaxies we find that no significant variations occur between the LF of the inner and outer part of the star-forming disk, whereas the LF in the spiral arm areas is shallower than in the inter-arm areas for six out of the 13 galaxies with clearly visible spiral arms. We attribute these variations to the spiral arms increasing the molecular clouds arm--inter-arm mass contrast and find suggestive evidence that they are more evident for galaxies with stronger spiral arms. Furthermore, we find systematic variations in $α$ between samples of HII regions with high and low ionization parameter q and argue that they are driven by the aging of HII regions.

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arXiv2021

The Blue Supergiant Progenitor of the Supernova Imposter AT~2019krl

Extensive archival \textit{Hubble Space Telescope}, \textit{Spitzer Space Telescope}, and Large Binocular Telescope imaging of the recent intermediate-luminosity transient, AT~2019krl in M74, reveal a bright optical and mid-infrared progenitor star. While the optical peak of the event was missed, a peak was detected in the infrared with an absolute magnitude of $M_{4.5\,μ{\rm m}} = -18.4$ mag, leading us to infer a visual-wavelength peak absolute magnitude of $-$13.5 to $-$14.5. The pre-discovery light curve indicated no outbursts over the previous 16\,yr. The colors, magnitudes, and inferred temperatures of the progenitor best match a 13--14 M$_{\sun}$ yellow or blue supergiant (BSG), if only foreground extinction is taken into account, or a hotter and more massive star, if any additional local extinction is included. A pre-eruption spectrum of the star reveals strong H$α$ and [N~{\sc ii}] emission with wings extending to $\pm 2000$\,km\,s$^{-1}$. The post-eruption spectrum is fairly flat and featureless with only H$α$, \ion{Na}{1}~D, [\ion{Ca}{2}], and the \ion{Ca}{2} triplet in emission. As in many previous intermediate-luminosity transients, AT~2019krl shows remarkable observational similarities to luminous blue variable (LBV) giant eruptions, SN~2008S-like events, and massive-star mergers. However, the information about the pre-eruption star favors either a relatively unobscured BSG or a more extinguished LBV with $M > 20$\,M$_{\sun}$ likely viewed pole-on.

astro-ph.SR↗

arXiv2021

PHANGS-ALMA: Arcsecond CO(2-1) Imaging of Nearby Star-Forming Galaxies

We present PHANGS-ALMA, the first survey to map CO J=2-1 line emission at ~1" ~ 100pc spatial resolution from a representative sample of 90 nearby (d<~20 Mpc) galaxies that lie on or near the z=0 "main sequence" of star-forming galaxies. CO line emission traces the bulk distribution of molecular gas, which is the cold, star-forming phase of the interstellar medium. At the resolution achieved by PHANGS-ALMA, each beam reaches the size of a typical individual giant molecular cloud (GMC), so that these data can be used to measure the demographics, life-cycle, and physical state of molecular clouds across the population of galaxies where the majority of stars form at z=0. This paper describes the scientific motivation and background for the survey, sample selection, global properties of the targets, ALMA observations, and characteristics of the delivered ALMA data and derived data products. As the ALMA sample serves as the parent sample for parallel surveys with VLT/MUSE, HST, AstroSat, VLA, and other facilities, we include a detailed discussion of the sample selection. We detail the estimation of galaxy mass, size, star formation rate, CO luminosity, and other properties, compare estimates using different systems and provide best-estimate integrated measurements for each target. We also report the design and execution of the ALMA observations, which combine a Cycle~5 Large Program, a series of smaller programs, and archival observations. Finally, we present the first 1" resolution atlas of CO emission from nearby galaxies and describe the properties and contents of the first PHANGS-ALMA public data release.

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arXiv2021

PHANGS-ALMA Data Processing and Pipeline

We describe the processing of the PHANGS-ALMA survey and present the PHANGS-ALMA pipeline, a public software package that processes calibrated interferometric and total power data into science-ready data products. PHANGS-ALMA is a large, high-resolution survey of CO J=2-1 emission from nearby galaxies. The observations combine ALMA's main 12-m array, the 7-m array, and total power observations and use mosaics of dozens to hundreds of individual pointings. We describe the processing of the u-v data, imaging and deconvolution, linear mosaicking, combining interferometer and total power data, noise estimation, masking, data product creation, and quality assurance. Our pipeline has a general design and can also be applied to VLA and ALMA observations of other spectral lines and continuum emission. We highlight our recipe for deconvolution of complex spectral line observations, which combines multiscale clean, single scale clean, and automatic mask generation in a way that appears robust and effective. We also emphasize our two-track approach to masking and data product creation. We construct one set of "broadly masked" data products, which have high completeness but significant contamination by noise, and another set of "strictly masked" data products, which have high confidence but exclude faint, low signal-to-noise emission. Our quality assurance tests, supported by simulations, demonstrate that 12-m+7-m deconvolved data recover a total flux that is significantly closer to the total power flux than the 7-m deconvolved data alone. In the appendices, we measure the stability of the ALMA total power calibration in PHANGS--ALMA and test the performance of popular short-spacing correction algorithms.

astro-ph.IM↗

arXiv2021

The SAMI Galaxy Survey: the third and final data release

We have entered a new era where integral-field spectroscopic surveys of galaxies are sufficiently large to adequately sample large-scale structure over a cosmologically significant volume. This was the primary design goal of the SAMI Galaxy Survey. Here, in Data Release 3 (DR3), we release data for the full sample of 3068 unique galaxies observed. This includes the SAMI cluster sample of 888 unique galaxies for the first time. For each galaxy, there are two primary spectral cubes covering the blue (370-570nm) and red (630-740nm) optical wavelength ranges at spectral resolving power of R=1808 and 4304 respectively. For each primary cube, we also provide three spatially binned spectral cubes and a set of standardized aperture spectra. For each galaxy, we include complete 2D maps from parameterized fitting to the emission-line and absorption-line spectral data. These maps provide information on the gas ionization and kinematics, stellar kinematics and populations, and more. All data are available online through Australian Astronomical Optics (AAO) Data Central.

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arXiv2020

Measuring the mixing scale of the ISM within nearby spiral galaxies

The spatial distribution of metals reflects, and can be used to constrain, the processes of chemical enrichment and mixing. Using PHANGS-MUSE optical integral field spectroscopy, we measure the gas phase oxygen abundances (metallicities) across 7,138 HII regions in a sample of eight nearby disc galaxies. In Paper I (Kreckel et al. 2019) we measure and report linear radial gradients in the metallicities of each galaxy, and qualitatively searched for azimuthal abundance variations. Here, we examine the two-dimensional variation in abundances once the radial gradient is subtracted, Delta(O/H), in order to quantify the homogeneity of the metal distribution and to measure the mixing scale over which HII region metallicities are correlated. We observe low (0.03--0.05 dex) scatter in Delta(O/H) globally in all galaxies, with significantly lower (0.02--0.03 dex) scatter on small (<600 pc) spatial scales. This is consistent with the measurement uncertainties, and implies the two-dimensional metallicity distribution is highly correlated on scales of <600 pc. We compute the two point correlation function for metals in the disc in order to quantify the scale lengths associated with the observed homogeneity. This mixing scale is observed to correlate better with the local gas velocity dispersion (of both cold and ionized gas) than with the star formation rate. Selecting only HII regions with enhanced abundances relative to a linear radial gradient, we do not observe increased homogeneity on small scales. This suggests that the observed homogeneity is driven by the mixing introducing material from large scales rather than by pollution from recent and on-going star formation.

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arXiv2019

Mapping electron temperature variations across a spiral arm in NGC 1672

We report one of the first extragalactic observations of electron temperature variations across a spiral arm. Using MUSE mosaic observations of the nearby galaxy NGC 1672, we measure the [N II]5755 auroral line in a sample of 80 HII regions in the eastern spiral arm of NGC1672. We discover systematic temperature variations as a function of distance perpendicular to the spiral arm. The electron temperature is lowest on the spiral arm itself and highest on the downstream side. Photoionization models of different metallicity, pressure, and age of the ionizing source are explored to understand what properties of the interstellar medium drive the observed temperature variations. An azimuthally varying metallicity appears to be the most likely cause of the temperature variations. The electron temperature measurements solidify recent discoveries of azimuthal variations of oxygen abundance based on strong lines, and rule out the possibility that the abundance variations are artefacts of the strong-line calibrations.

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arXiv2019

Calibrating star-formation rate prescriptions at different scales (10 pc to 1 kpc) in M31

We calibrate commonly used star formation rate (SFR) prescriptions using observations in five kpc-sized fields in the nearby galaxy Andromeda (M31) at 10\,pc spatial resolution. Our observations at different scales enable us to resolve the star-forming regions and to distinguish them from non star-forming components. We use extinction corrected H$α$ from optical integral field spectroscopy as our reference tracer and have verified its reliability via tests. It is used to calibrate monochromatic and hybrid (H$α$+a$\times$IR and FUV+b$\times$IR) SFR prescriptions, which use FUV (GALEX), 22\,$μ$m (WISE) and 24\,$μ$m (MIPS). Additionally, we evaluate other multi-wavelength infra-red tracers. Our results indicate that the SFR prescriptions do not change (in M31) with spatial scales or with subtraction of the diffuse component. For the calibration factors in the hybrid SFR prescriptions, we find a$\approx$0.2 and b$\approx$22 in M31, which are a factor of 5 higher than in the literature. As the fields in M31 exhibit high attenuation and low dust temperatures, lie at large galacto-centric distances, and suffer from high galactic inclination compared to measurements in other galaxies, we propose that the fields probe a dust layer extended along the line of sight that is not directly spatially associated with star-forming regions. This (vertically) extended dust component increases the attenuation and alters the SFR prescriptions in M31 compared to literature measurements. We recommend that SFR prescriptions should be applied with caution at large galacto-centric distances and in highly inclined galaxies, due to variations in the relative (vertical) distribution of dust and gas.

astro-ph.GA↗

arXiv2016

The SAMI Galaxy Survey: Revisiting Galaxy Classification Through High-Order Stellar Kinematics

Recent cosmological hydrodynamical simulations suggest that integral field spectroscopy can connect the high-order stellar kinematic moments h3 (~skewness) and h4 (~kurtosis) in galaxies to their cosmological assembly history. Here, we assess these results by measuring the stellar kinematics on a sample of 315 galaxies, without a morphological selection, using 2D integral field data from the SAMI Galaxy Survey. A proxy for the spin parameter ($λ_{R_e}$) and ellipticity ($ε_e$) are used to separate fast and slow rotators; there exists a good correspondence to regular and non-regular rotators, respectively, as also seen in earlier studies. We confirm that regular rotators show a strong h3 versus $V/σ$ anti-correlation, whereas quasi-regular and non-regular rotators show a more vertical relation in h3 and $V/σ$. Motivated by recent cosmological simulations, we develop an alternative approach to kinematically classify galaxies from their individual h3 versus $V/σ$ signatures. We identify five classes of high-order stellar kinematic signatures using Gaussian mixture models. Class 1 corresponds to slow rotators, whereas Classes 2-5 correspond to fast rotators. We find that galaxies with similar $λ_{R_e}-ε_e$ values can show distinctly different h3-$V/σ$ signatures. Class 5 objects are previously unidentified fast rotators that show a weak h3 versus $V/σ$ anti-correlation. These objects are predicted to be disk-less galaxies formed by gas-poor mergers. From morphological examination, however, there is evidence for large stellar disks. Instead, Class 5 objects are more likely disturbed galaxies, have counter-rotating bulges, or bars in edge-on galaxies. Finally, we interpret the strong anti-correlation in h3 versus $V/σ$ as evidence for disks in most fast rotators, suggesting a dearth of gas-poor mergers among fast rotators.

astro-ph.GA↗

arXiv2014

IFU observations of luminous type II AGN - I. Evidence for ubiquitous winds

We present observations of 17 luminous (log(L[O III]/L_Sun) > 8.7) local (z < 0.11) type II AGN. Our aim is to investigate the prevalence and nature of AGN driven outflows in these galaxies by combining kinematic and ionization diagnostic information. We use non-parametric methods (e.g. W80, the width containing 80% of the line flux) to assess the line widths in the central regions of our targets. The maximum values of W80 in each galaxy are in the range 400 - 1600 km/s, with a mean of 790 +- 90 km/s. Such high velocities are strongly suggestive that these AGN are driving ionized outflows. Multi-Gaussian fitting is used to decompose the velocity structure in our galaxies. 14/17 of our targets require 3 separate kinematic components in the ionized gas in their central regions. The broadest components of these fits have FWHM = 530 - 2520 km/s, with a mean value of 920 +- 50 km/s. By simultaneously fitting both the Hβ/[O III] and Hα/[N II] complexes we construct ionization diagnostic diagrams for each component. 13/17 of our galaxies show a significant (> 95 %) correlation between the [N II]/Hα ratio and the velocity dispersion of the gas. Such a correlation is the natural consequence of a contribution to the ionization from shock excitation and we argue that this demonstrates that the outflows from these AGN are directly impacting the surrounding ISM within the galaxies.

astro-ph.GA↗