A new diagnostic to separate line emission from star formation, shocks, and AGNs simultaneously in IFU data

D'Agostino, Joshua; Kewley, Lisa J.; Groves, Brent; Medling, Anne M.; Dopita, Michael A.; Thomas, Amberyn

doi:10.1093/mnrasl/slz028

Cited by 53 publications

(20 citation statements)

References 28 publications

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“…This begs the question of whether the [O III] lines are always related to the central AGN. Indeed, several studies have shown that while the optical line diagnostics can reasonably well separate AGNs and SFs, they are not able to differentiate between line emission arising from non-nuclear shocked gas and that of the AGN (Monreal-Ibero et al 2010;Rich et al 2015;D'Agostino et al 2019;P. Väisänen, private communication) These alternative scenarios may be investigated using X-ray data to check the presence of a torus and using long-slit spectroscopy to map the [O III] distribution notably in the circumnuclear SF rings.…”

Section: Discussionmentioning

confidence: 99%

Galaxy and Mass Assembly (GAMA): A WISE Study of the Activity of Emission-line Systems in G23

Yao

Jarrett

Cluver

et al. 2020

ApJ

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We present a detailed study of emission-line systems in the Galaxy And Mass Assembly (GAMA) G23 region, making use of Wide-field Infrared Survey Explorer (WISE) photometry that includes carefully measured resolved sources. After applying several cuts to the initial catalog of ∼41,000 galaxies, we extract a sample of 9809 galaxies. We then compare the spectral diagnostic Baldwin, Philips & Terlevich (BPT) classification of 1154 emission-line galaxies (38% resolved in W1) to their location in the WISE color-color diagram, leading to the creation of a new zone for mid-infrared "warm" galaxies located 2σ above the star-forming sequence, below the standard WISE active galactic nucleus (AGN) region. We find that the BPT and WISE diagrams agree on the classification for 85% and 8% of the galaxies as non-AGN (star-forming=SF) and AGN, respectively, and disagree on ∼7% of the entire classified sample. Thirty-nine percent of the AGNs (all types) are broad-line systems for which the [N II] and [Hα] fluxes can barely be disentangled, giving in most cases spurious [N II]/[Hα] flux ratios. However, several optical AGNs appear to be completely consistent with SF in WISE. We argue that these could be low-power AGNs, or systems whose hosts dominate the IR emission. Alternatively, given the sometimes high [O III] luminosity in these galaxies, the emission lines may be generated by shocks coming from super-winds associated with SF rather than AGN activity. Based on our findings, we have created a new diagnostic: [W1 -W2] versus [N II]/ [Hα], which has the virtue of separating SF from AGNs and high-excitation sources. It classifies 3to ∼5 times more galaxies than the classic BPT.Unified Astronomy Thesaurus concepts: Galaxy evolution (594); AGN host galaxies (2017); Infrared galaxies (790)

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Section: Discussionmentioning

confidence: 99%

Galaxy and Mass Assembly (GAMA): A WISE Study of the Activity of Emission-line Systems in G23

Yao

Jarrett

Cluver

et al. 2020

ApJ

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“…Like in the previous case, the complexity of the ionization would be impossible to uncover without a detailed exploration of the shape, distribution, and location in the different diagnostic diagrams, together with the use of the EW(Hα) and the comparison with the spatial distribution of the continuum emission (either stellar or the radio-jet). Additional information, as provided by the gas and stellar kinematics (and the comparison between them), and an analysis of the velocity dispersion and asymmetry of the lines helps to disentangle the real nature of such ionizing sources (D'Agostino et al 2019;López-Cobá et al 2020).…”

Section: Spatial Distribution Of the Ionized Gasmentioning

confidence: 99%

From Global to Spatially Resolved in Low-Redshift Galaxies

Sanchez¹,

Walcher

López-Cobá³

et al. 2021

RMxAA

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Our understanding of the structure, composition and evolution of galaxies hasstrongly improved in the last decades, mostly due to new results based on large spectro-scopic and imaging surveys. In particular, the nature of ionized gas, its ionization mech-anisms, its relation with the stellar properties and chemical composition, the existence ofscaling relations that describe the cycle between stars and gas, and the corresponding evo-lution patterns have been widely explored and described. More recently, the introduction ofadditional techniques, in particular integral field spectroscopy, and their use in large galaxysurveys, have forced us to re-interpret most of those recent results from a spatially resolvedperspective. This review is aimed to complement recent efforts to compile and summarizethis change of paradigm in the interpretation of galaxy evolution. To this end we replicatepublished results, and present novel ones, based on the largest compilation of IFS data ofgalaxies in the nearby universe to date.

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“…Scholtz et al 2020). In addition, Hα can suffer from significant obscuration (see also Kewley et al 2013a;D'Agostino et al 2019). Therefore, if we want to use Hα as a SFR tracer we need to determine what is the dominant contributor to the line emission and whether we can identify a component of the Hα emission that can be used to trace star formation in our sample.…”

Section: Origin Of the Hα Emissionmentioning

confidence: 99%

Super

Lamperti

Harrison

Mainieri

et al. 2021

A&A

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We study the impact of active galactic nuclei (AGN) ionised outflows on star formation in high-redshift AGN host galaxies, by combining near-infrared integral field spectroscopic (IFS) observations, mapping the Hα emission and [O III]λ5007 outflows, with matched-resolution observations of the rest-frame far-infrared (FIR) emission. We present high-resolution ALMA Band 7 observations of eight X-ray selected AGN (L2 − 10 keV = 1043.8 − 1045.2 erg s−1) at z ∼ 2 from the SUPER (SINFONI Survey for Unveiling the Physics and Effect of Radiative feedback) sample, targeting the observed-frame 870 μm (rest-frame ∼260 μm) continuum at ∼2 kpc (0.2″) spatial resolution. The targets were selected among the SUPER AGN with an [O III] detection in the IFS maps and with a detection in the FIR photometry. We detected six out of eight targets with signal-to-noise ratio S/N ≳ 10 in the ALMA maps, from which we measured continuum flux densities in the range 0.27 − 2.58 mJy and FIR half-light radii (Re) in the range 0.8 − 2.1 kpc. The other two targets were detected with S/N of 3.6 and 5.9, which are insufficient for spatially resolved analysis. The FIR Re of our sample are comparable to other AGN and star-forming galaxies at a similar redshift from the literature. However, combining our sample with the literature samples, we find that the mean FIR size in X-ray AGN (Re = 1.16 ± 0.11 kpc) is slightly smaller than in non-AGN (Re = 1.69 ± 0.13 kpc). From spectral energy distribution fitting, we find that the main contribution to the 260 μm flux density is dust heated by star formation, with ≤4% contribution from AGN-heated dust and ≤1% from synchrotron emission. The majority of our sample show different morphologies for the FIR (mostly due to reprocessed stellar emission) and the ionised gas emission (Hα and [O III], mostly due to AGN emission). This could be due to the different locations of dust and ionised gas, the different sources of the emission (stars and AGN), or the effect of dust obscuration. We are unable to identify any residual Hα emission, above that dominated by AGN, that could be attributed to star formation. Under the assumption that the FIR emission is a reliable tracer of obscured star formation, we find that the obscured star formation activity in these AGN host galaxies is not clearly affected by the ionised outflows. However, we cannot rule out that star formation suppression is happening on smaller spatial scales than the ones we probe with our observations (< 2 kpc) or on different timescales.

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A new diagnostic to separate line emission from star formation, shocks, and AGNs simultaneously in IFU data

Cited by 53 publications

References 28 publications

Galaxy and Mass Assembly (GAMA): A WISE Study of the Activity of Emission-line Systems in G23

Galaxy and Mass Assembly (GAMA): A WISE Study of the Activity of Emission-line Systems in G23

From Global to Spatially Resolved in Low-Redshift Galaxies

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