scholarly journals High-Ionization Nuclear Emission-Line Region of Seyfert Galaxies

2000 ◽  
Vol 119 (6) ◽  
pp. 2605-2628 ◽  
Author(s):  
Tohru Nagao ◽  
Yoshiaki Taniguchi ◽  
Takashi Murayama
Keyword(s):  
Emission Line ◽  
Seyfert Galaxies ◽  
Line Region ◽  
High Ionization

scholarly journals Dust Distribution in IRAS Seyfert Galaxies

1994 ◽  
Vol 159 ◽  
pp. 355-355
Author(s):  
M. G. Pastoriza ◽  
Charles Bonatto ◽  
Eduardo Bica ◽  
T. Storchi-Bergmann
Keyword(s):  
Emission Line ◽  
Power Law ◽  
Dust Emission ◽  
Seyfert Galaxies ◽  
Emission Model ◽  
Line Region ◽  
Population Type ◽  
The Galaxy ◽  
Dilution Effects ◽  
Dust Distribution

Observational evidences of dust in the nuclear region of AGNs are substantial (Rudy 1984, ApJ, 284, 33; Jones et al. 1984, PASP, 96, 692). The ionization cones observed in several Seyfert galaxies has been interpreted as shadowing effects by a dust obscuring torus which hides the broad emission line region (BLR) and the central source (Wilson 1992; Storchi-Bergmann, Mulchaey and Wilson 1992, ApJ 395, L73). A large sample of optical and far-IR data for IRAS Seyfert galaxies has been analysed together with dust emission models (Bonatto and Pastoriza 1993), where it has been concluded that the same dust emission model can be applied to both Seyfert types. In order to further study the effects of dust in the spectra of active galactic nuclei, we have obtained spectrophotometry of 21 IRAS Seyfert galaxies in the range 3500–7200 Å and analyse them in conjuction with their IRAS fluxes. The stellar population type is derived from comparisons with normal galaxy templates using dilution effects in the K CaII line as discriminator. For 55% of the sample the population is of late type. For the rest, blue continua due to recent star formation and/or power-law may amount up to 30% at 4000Å. We conclude that the bulge stellar populations of IRAS Seyfert galaxies are similar to those of normal spirals, except that they are more reddened by E(B-V)i ∼ 0.20. Population-subtracted emission line ratios indicate on average stronger reddening for the narrow-line region (E(B-V)l ∼ 0.8. From photoionization models a power-law index for the ionizing continuum α=1.5, and a metallicity larger than solar are obtained. The most luminous IRAS galaxy of the sample (IRAS555) is discuss in detail: in order to be compatible with the observed IRAS fluxes and the optical stellar continuum, the ionizing continuum must be reddened by AV > 10 magnitudes. Consequently a dust structure in this galaxy appears to be increasingly affecting stars and gas towards the galaxy center.

scholarly journals High-Ionization Nuclear Emission-Line Region in the Seyfert Galaxy Tololo 0109−383

1998 ◽  
Vol 115 (2) ◽  
pp. 460-471 ◽  
Author(s):  
Takashi Murayama ◽  
Yoshiaki Taniguchi ◽  
Kazushi Iwasawa
Keyword(s):  
Emission Line ◽  
Seyfert Galaxy ◽  
Line Region ◽  
High Ionization

scholarly journals The Coronal Emission-Line Region in AGNs: A Hubble Space Telescope View

2009 ◽  
Vol 5 (S267) ◽  
pp. 122-122
Author(s):  
X. Mazzalay ◽  
A. Rodríguez-Ardila ◽  
S. Komossa
Keyword(s):  
Physical Properties ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Hubble Space Telescope ◽  
Seyfert Galaxies ◽  
Coronal Line ◽  
Coronal Emission ◽  
Line Region ◽  
High Ionization ◽  
Coronal Emission Line

AbstractWe present a study of HST/STIS optical spectra of a sample of ten Seyfert galaxies aimed at analyzing the structure and physical properties of the coronal line region. The high spatial resolution provided by STIS (about 7 pc for the closest objects) allowed us to resolve the coronal line region and obtain key information about the kinematics of the coronal-line gas, measure directly its spatial scale, and study the mechanisms that drive the high-ionization lines.

Subaru Spectropolarimetry of Markarian 573: The Hidden High-Ionization Nuclear Emission-Line Region inside the Dusty Torus

2004 ◽  
Vol 128 (5) ◽  
pp. 2066-2072 ◽  
Author(s):  
Tohru Nagao ◽  
Koji S. Kawabata ◽  
Takashi Murayama ◽  
Youichi Ohyama ◽  
Yoshiaki Taniguchi ◽  
...  
Keyword(s):  
Emission Line ◽  
Line Region ◽  
High Ionization ◽  
Dusty Torus

scholarly journals The nature of LINER galaxies: Ubiquitous hot old stars and rare accreting black holes

2013 ◽  
Vol 9 (S304) ◽  
pp. 280-281
Author(s):  
R. Singh ◽  
G. van de Ven ◽  
K. Jahnke ◽  
Keyword(s):  
Emission Line ◽  
Surface Brightness ◽  
Seyfert Galaxies ◽  
Central Mass ◽  
Massive Galaxies ◽  
Line Region ◽  
Liner Galaxies ◽  
New Interpretation ◽  
Most Probable Explanation ◽  
Integral Field

AbstractGalaxies, which often contain ionised gas, sometimes also exhibit a so-called low-ionisation nuclear emission line region (LINER). For 30 years, this was attributed to a central mass-accreting supermassive black hole (more commonly known as active galactic nucleus or AGN) of low luminosity, making LINER galaxies the largest AGN sub-population, which dominate in numbers over higher AGN-luminosity Seyfert galaxies and quasars. This, however, poses a serious problem. While the inferred energy balance is plausible, many LINERs clearly do not contain any other independent signatures of an AGN. Using integral field spectroscopic data from the CALIFA survey, we compare the observed radial surface brightness profiles with what is expected from illumination by an AGN. For 48 galaxies with LINER-like emission we show, that the radial emission-line surface brightness profiles are inconsistent with ionisation by a central point-source and hence cannot be due to an AGN alone. The most probable explanation for the excess LINER-like emission is ionisation by evolved stars during the short but very hot and energetic phase known as post-AGB. This leads us to an entirely new interpretation. Post-AGB stars are ubiquitous and their ionising effect should be potentially observable in every galaxy with gas present and with stars older than ~1 Gyr, unless a stronger radiation field from young hot stars or an AGN outshines them. This means, that galaxies with LINER-like emission are not a class defined by a property but rather by the absence of a property. It also explains why LINER emission is observed mostly in massive galaxies with old stars and little star formation.

scholarly journals Properties of Warm Absorbers and Constraints from their Optical and UV Line Emission

1997 ◽  
Vol 159 ◽  
pp. 246-247
Author(s):  
Stefanie Komossa ◽  
Henner Fink
Keyword(s):  
Line Emission ◽  
Seyfert Galaxies ◽  
Coronal Line ◽  
X Ray ◽  
Line Region ◽  
High Ionization ◽  
Photon Index ◽  
Balmer Lines ◽  
The Individual ◽  
Ionization Parameter

We have studied the warm absorbers in several Seyfert galaxies using both PI and archival ROSAT data. The parameters that govern the emissivity of the ionized material, ionization parameter U, warm-absorber column density Nwa, and the source intrinsic power-law photon index Γx, are determined from X-ray spectral fits. These are then used to predict the expected IR to UV line emission of the ionized material in the individual objects. In particular, the possibility of a warm-absorber origin of one of the known emission-line regions in AGN is assessed. Good ‘candidate components’ are, e.g., the coronal-line region, and/or the high-ionization component of the NLR, or the component responsible for broad wings in the Balmer lines. All calculations have been carried out using the code CLOUDY (Ferland 1993).

scholarly journals Extended High-Ionization Nuclear Emission-Line Region in the Seyfert Galaxy NGC 4051

2000 ◽  
Vol 119 (2) ◽  
pp. 620-630 ◽  
Author(s):  
Tohru Nagao ◽  
Takashi Murayama ◽  
Yoshiaki Taniguchi ◽  
Michitoshi Yoshida
Keyword(s):  
Emission Line ◽  
Seyfert Galaxy ◽  
Line Region ◽  
High Ionization ◽  
Ngc 4051

scholarly journals Substructures in the Narrow-Line Region of AGN

1989 ◽  
Vol 134 ◽  
pp. 312-313
Author(s):  
Sylvain Veilleux
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Seyfert Galaxies ◽  
Narrow Line ◽  
Line Profiles ◽  
Preliminary Results ◽  
Line Region ◽  
Narrow Line Region ◽  
Narrow Emission ◽  
Resolution Study

The preliminary results of a high-resolution study of narrow emission-line profiles in bright Seyfert galaxies are reported. Profile substructures such as secondary peaks and shoulders are observed in nearly all the objects. The results of profile comparisons in Mrk 359, Mrk 533, and Mrk 1066 are briefly discussed.

scholarly journals The MURALES survey

2018 ◽  
Vol 619 ◽  
pp. A83 ◽  
Author(s):  
B. Balmaverde ◽  
A. Capetti ◽  
A. Marconi ◽  
G. Venturi ◽  
M. Chiaberge ◽  
...  
Keyword(s):  
Emission Line ◽  
Point Of View ◽  
Ionized Gas ◽  
Very Large Telescope ◽  
Line Region ◽  
High Ionization ◽  
Line Widths ◽  
Bright Emission ◽  
Bright Emission Line

We observed the FR II radio galaxy 3C 459 (z = 0.22) with the MUSE spectrograph at the Very Large Telescope (VLT) as part of the MURALES project (a MUse RAdio Loud Emission line Snapshot survey). We detected diffuse nuclear emission and a filamentary ionized gas structure forming a one-sided, triangular-shaped region extending out to ∼80 kpc. The central emission line region is dominated by two compact knots of similar flux: the first (N1) cospatial with the radio core and the (N2) second located 1″.2 (5.3 kpc) to the SE. The two regions differ dramatically from the point of view of velocity (with an offset of ∼400 km s−1), line widths, and line ratios. This suggests that we are observing a dual AGN system formed by a radio loud AGN and type 2 QSO companion, which is the result of the recent merger that also produced its disturbed host morphology. The alternative possibility that N2 is just a bright emission line knot resulting from, for example, a jet-cloud interaction, is disfavored because of (1) the presence of a high ionization bicone whose apex is located at N2; (2) the observed narrow line widths; (3) its line luminosity (∼1042 erg s−1) typical of luminous QSOs; and (4) its location, which is offset from the jet path. The putative secondary AGN must be highly obscured, since we do not detect any emission in the Chandra and infrared Hubble Space Telescope images.

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