Are the Narrow-Line Regions in Active Galaxies Dusty and Radiation Pressure Dominated?

By M. Dopita, B. Groves, R. Sutherland, L. Binette, G. Cecil. 2002

158 citations recorded by the source corpus.

The remarkable similarity between emission spectra of narrow-line regions (NLRs) in Seyfert galaxies has long presented a mystery. In photoionization models, this similarity implies that the ionization parameter is nearly always the same, about U ~ 0.01. Here we present dusty, radiation pressure-dominated photoionization models that can provide natural physical insight into this problem. In these models, dust and the radiation pressure acting upon it provide the controlling factor in moderating the density, excitation, and surface brightness of photoionized NLR structures. Additionally, photoelectric heating by the dust is important in determining the temperature structure of the models. These models can also explain the coexistence of the low-, intermediate-, and coronal ionization zones within a single self-consistent physical structure. The radiation pressure acting on dust may also be capable of driving the fast (~3000 km s-1) outflows such as are seen in the HST observations of NGC 1068.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/e8a0bffedb78c348929810106d073593795c0173

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Citations in the corpus

• A Hubble Space Telescope Survey of Extended [O III] λ5007 Å Emission in a Far-Infrared-Selected Sample of Seyfert Galaxies: Results (2003, background): “This result also agrees with those obtained from photoionization models, which indicate that single zone models are not an appropriate representation for NLR’s (Dopita et al. 2002; Binette, Wilson & Storchi-Bergmann 1996).”
• OUTFLOWS FROM ACTIVE GALACTIC NUCLEI: KINEMATICS OF THE NARROW-LINE AND CORONAL-LINE REGIONS IN SEYFERT GALAXIES, (2011, background): “…photoionization by the central continuum source plays a dominant role in exciting the gas (e.g., Kraemer & Crenshaw 2000a; Kraemer et al. 2000; Bennert et al. 2006) although shocks may play an important role in localized regions (Kraemer & Crenshaw 2000b; Dopita et al. 2002; Contini et al. 2009).”
• Dusty, Radiation Pressure-Dominated Photoionization. I. Model Description, Structure, and Grids (2004, background): “In an attempt to self-consistently address both the problems of the gas dynamics and of the wide range in observed excitation conditions that exist within the NLR, a new paradigm of dusty, radiation pressure dominated photoionization was developed (Dopita et al. 2002) (DG02).”
• Dusty, Radiation Pressure-Dominated Photoionization. II. Multiwavelength Emission Line Diagnostics for Narrow-Line Regions (2004, background): “In order to account for these failings of the standard models we have proposed a new paradigm for the photoionization of the NLR clouds, that of dusty, radiation pressure–dominated photoionization (Dopita et al. 2002, hereafter DG02).”
• NEW STRONG-LINE ABUNDANCE DIAGNOSTICS FOR H ii REGIONS: EFFECTS OF κ-DISTRIBUTED ELECTRON ENERGIES AND NEW ATOMIC DATA (2013, methodology): “For helium, we adopt a similar prescription as used by Dopita et al. (2002), which provides a good fit to the He abundances observed in H ii regions.”
• Discovery of extreme [O III] λ5007 Å outflows in high-redshift red quasars (2015, background): “For a more typical density of 103 cm−3 (Baskin & Laor 2005), the nominal emitting size is 14 kpc. Radiation-pressure-dominated models (Dopita et al. 2002; Stern et al. 2014b) suggest somewhat higher ionization parameters, between U = 0.01 and 0.1, but even in this case the emitting size is between…”
• The SAURON project - XVI. On the sources of ionization for the gas in elliptical and lenticular galaxies (2009, methodology): “If we disregard the latter possibility for the moment (see §3.4), we note that only models including gas of super-solar metallicity and a self-consistent treatment of dust (Dopita et al. 2002; Groves, Dopita, & Sutherland 2004) provide a plausible description for our data.”
• The MAPPINGS III Library of Fast Radiative Shock Models (2008, methodology): “For these, the radiation-pressureY dominated photoionization models (Dopita et al. 2002; Groves et al. 2004b, 2004c) provide a much better description of the MAPPINGS III SHOCK MODEL LIBRARY 53No. 1, 2008 spectra.”
• Fast neutral outflows in powerful radio galaxies : a major source of feedback in massive galaxies (2005, background): “Different mechanisms have been proposed to explain AGN-driven outflows (Tadhunter et al. 2001, Elvis et al. 2002, Dopita et al. 2002).”
• THE NATURE OF LINER-LIKE EMISSION IN RED GALAXIES (2011, methodology): “It may be possible to fit the [S II]/Hα ratios by tweaking the N/S abundance ratio, or adopting the dusty, radiation-pressure dominated photoionization model (Dopita et al. 2002).”
• On the Nature of Seyfert Galaxies with High [O III] λ5007 Blueshifts (2008, background): “…NLR (and CLR) include radiation pressure acting on gas (Binette et al. 1997, Das et al. 2007) and on dust grains embedded in the clouds (Binette 1998, Dopita et al. 2002), and the entrainment of NLR clouds in hot winds (Krolik & Vrtilek 1984, Schiano 1986, Mathews & Veilleux 1989, Smith 1993,…”
• Mapping Large-Scale Gaseous Outflows in Ultraluminous Galaxies with Keck II ESI Spectra: Variations in Outflow Velocity with Galactic Mass (2004, background): “The radiative force on the gas clouds is Frad = Mcc −1 ∫ κνFνdν, where the absorption opacity of the dust and gas mixture, κ, drops from 12 For this to be strictly true, the ionization parameter must exceed U0 ≈ 0.01 (Dopita et al. 2002).”
• SDSS IV MaNGA – spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs (2016, background): “In these models, for ionisation parameters greater than U ∼ αB/(c κd)∼ 10−2, where αB is the case B recombination coefficient for hydrogen and κd is the dust effective opactiy, the narrow line region is radiation pressure-dominated (Dopita et al. 2002).”
• Size and Structure of the Narrow-Line Region of Quasars (2002, background): “More recently, Dopita et al. (2002) use radiation–pressure dominated photoionization models to explain a constant ionization parameter (in the range of –2.5 ≤ log U ≤ –2).”
• Fitting the integrated spectral energy distributions of galaxies (2010, background): “…for star-forming galaxies (see e.g. Kewley et al. 2001), meaning negligible EUV absorption by dust in typical H II regions (<5%), but such high values may be reached within compact H II regions and AGN meaning dust will absorb a significant fraction of EUV photons (Dopita et al. 2002; Draine 2010).”
• Nuclear activity versus star formation: emission-line diagnostics at ultraviolet and optical wavelengths (2015, background): “…absorption and scattering of incident radiation, radiation pressure, collisional cooling and photoelectric heating of the gas (see, e.g., Ferland 1996, but also Shields & Kennicutt 1995, Dopita et al. 2002 and Groves et al. 2004a for a description of these effects on the emergent nebular emission).”
• Fueling Low-Level AGN Activity through Stochastic Accretion of Cold Gas (2006, background): “…disk winds (e.g., Konigl & Kartje 1994), MHD jet outflows (e.g., Blandford & Payne 1982) powered by magnetic coronae formation over the disk (Miller & Stone 2000), Comptonization in an X-ray halo (e.g., Begelman 1985), and radiation pressure coupling to dust opacity (e.g., Dopita et al. 2002).”