Size and properties of the narrow-line region in Seyfert-1 galaxies from spatially-resolved optical spectroscopy

By N. Bennert, B. Jungwiert, S. Komossa, M. Haas, Rolf Chini Airub Univ. Bochum, Igpp UC Riverside, Astronomical Institute Prague, C. Lyon, Mpe Garching. 2006

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Context. Spatially resolved emission-line spectroscopy is a powerful tool for determining the physical conditions in the narrow-line region (NLR) of active galactic nuclei (AGNs). We recently used optical long-slit spectroscopy to study the NLRs of a sample of six Seyfert-2 galaxies. We have shown that such an approach, in comparison to the commonly used [O III] narrow-band imaging alone, allows us to probe the size of the NLR in terms of AGN photoionisation. Moreover, several physical parameters of the NLR can be directly accessed. Aims. We here apply the same methods to study the NLR of six Seyfert-1 galaxies and compare our results to those of Seyfert-2 galaxies. Methods. We employ diagnostically valuable emission-line ratios to determine the physical properties of the NLR, including the core values and radial dependencies of density, ionisation parameter, and reddening. Tracking the radial change of emission-line ratios in diagnostic diagrams allows us to measure the transition between AGN-like and H II-like line excitation, and thus to measure the size of the NLR. Results. In the diagnostic diagrams, we find a transition between line ratios falling in the AGN regime and those typical of H II regions in two Seyfert-1 galaxies, thereby determining the size of the NLR. The central electron temperature and ionisation parameter are, in general, higher in type-1 Seyferts than in type 2s. In almost all cases, both electron density and ionisation parameter decrease with radius and the decrease is faster in Seyfert-1 galaxies than in Sy2s. In several objects, the gaseous velocity distribution is characteristic of rotational motion in an (inclined) emission-line disk in the centre. We give estimates of the black-hole masses and discuss our findings in detail for each object.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/57bb72cdd1a786ac7b4232dd3a456149e39aaccd

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Citations in the corpus

Observations of feedback from radio-quiet quasars - I. Extents and morphologies of ionized gas nebulae (2013, methodology): “We adopt the uncertainties estimated by Fraquelli et al. (2003) for their objects, while for the five Bennert et al. (2006) objects we propagate the uncertainties in the best-fit power indices to Rint.”
Nuclear Activity in Nearby Galaxies (2008, background): “5 (Bennert et al. 2006), LINERs seem to be significantly more compact.”
On the Nature of Seyfert Galaxies with High [O III] λ5007 Blueshifts (2008, background): “…the ratio of [OIII]/[SII] of nearby Seyfert galaxies generally decreases in dependence of radius (in models and observations; Komossa & Schulz 1997, Bennert et al. 2006) and since there must be an [OIII] contribution from the outer [SII] emitting clouds, the limits derived on any nonblueshifted…”
Galaxy Zoo: 'Hanny's Voorwerp', a quasar light echo? (2009, methodology): “1.02 ± 0.05 we derive an electron density of ∼560 ± 150 cm−3 for the centre of IC 2497, similar to values found for the narrowline region in Seyfert galaxies (Peterson 2003; Bennert et al. 2006; Osterbrock & Ferland 2006).”
OUTFLOWS FROM ACTIVE GALACTIC NUCLEI: KINEMATICS OF THE NARROW-LINE AND CORONAL-LINE REGIONS IN SEYFERT GALAXIES, (2011, methodology): “If this calculation were performed for the NLR, Ne would be smaller, 102 < Ne < 103 cm−3, and f would be larger, 0.01 < f < 0.1 (Taylor et al. 2003; Bennert et al. 2006; Storchi-Bergmann et al. 2010).”
Quasar feedback and the origin of radio emission in radio-quiet quasars (2014, result): “…Small Magellanic Cloud extinction curve from Weingartner & Draine (2001) are in the range AV = 1.0− 1.5 mag, in agreement with our previous estimates for type 2 quasars (Reyes et al. 2008) and with typical values in the literature for narrow-line regions of Seyfert galaxies (Bennert et al. 2006).”
FEEDBACK IN LUMINOUS OBSCURED QUASARS (2011, methodology): “Obscuration, Ionization, and Excitation NLR sizes have been measured from narrow-band imaging (Mulchaey et al. 1996a; Bennert et al. 2002; Schmitt et al. 2003) and from long-slit spectroscopy (e.g., Unger et al. 1987; Fraquelli et al. 2003; Bennert et al. 2006).”
The SAMI Galaxy Survey: shocks and outflows in a normal star-forming galaxy (2014, background): “Outflows in narrow line regions (NLRs) in Seyfert galaxies are typically confined to the c© 0000 RAS, MNRAS 000, 000–000 kiloparsec to sub-kiloparsec scale (Bennert et al. 2006a,b; Fischer et al. 2013), and NLRs in LINERs are smaller, few tens to few hundred parsecs (Masegosa et al. 2011).”
THEORETICAL EVOLUTION OF OPTICAL STRONG LINES ACROSS COSMIC TIME (2013, background): “The narrowline region surrounding an AGN is typically 1-5 kpc (Bennert et al. 2006), smaller than the typical radius sampled by global spectra of local pure star-forming galaxies (∼ 8 kpc on average; Kewley et al. 2004).”