scholarly journals Impact of nuclear activity on extended emission line regions of nearby galaxies

1995 ◽  
Vol 149 ◽  
pp. 269-273
Author(s):  
E. Pécontal ◽  
P. Ferruit ◽  
A.S. Wilson
Keyword(s):  
Emission Line ◽  
Seyfert Galaxies ◽  
Emission Lines ◽  
Nuclear Activity ◽  
Central Engine ◽  
Nearby Galaxies ◽  
The Impact ◽  
Integral Field ◽  
Extended Emission ◽  
Narrow Emission

AbstractWe used the integral field TIGER to map the intensity ratios of emission lines and the velocity field over the narrow emission line of a few nearby Seyfert galaxies. Our aim is to study the impact of nuclear activity on galaxies, which will hopefully help us to probe the central engine. We present here some results for two objects: M 51 and NGC 5929.

scholarly journals Gaia-assisted discovery of a detached low-ionisation BAL quasar with very large ejection velocities

2020 ◽  
Vol 634 ◽  
pp. A111 ◽  
Author(s):  
J. P. U. Fynbo ◽  
P. Møller ◽  
K. E. Heintz ◽  
J. N. Burchett ◽  
L. Christensen ◽  
...  
Keyword(s):  
Emission Line ◽  
Absorption Line ◽  
Emission Lines ◽  
Broad Absorption ◽  
Broad Absorption Line ◽  
Red Edge ◽  
First Case ◽  
Bl Lac ◽  
Spatially Extended ◽  
Extended Emission

We report on the discovery of a peculiar broad absorption line (BAL) quasar identified in our Gaia-assisted survey of red quasars. The systemic redshift of this quasar was difficult to establish because of the absence of conspicuous emission lines. Based on deep and broad BAL troughs of at least Si IV, C IV, and Al III, a redshift of z = 2.41 was established under the assumption that the systemic redshift can be inferred from the red edge of the BAL troughs. However, we observe a weak and spatially extended emission line at 4450 Å that is most likely due to Lyman-α emission, which implies a systemic redshift of z = 2.66 if correctly identified. There is also evidence for the onset of Lyman-α forest absorption bluewards of 4450 Å and evidence for Hα emission in the K band consistent with a systemic redshift of z = 2.66. If this redshift is correct, the quasar is an extreme example of a detached low-ionisation BAL quasar. The BALs must originate from material moving with very large velocities ranging from 22 000 km s−1 to 40 000 km s−1. To our knowledge, this is the first case of a systemic-redshift measurement based on extended Lyman-α emission for a BAL quasar. This method could also be useful in cases of sufficiently distant BL Lac quasars without systemic-redshift information.

scholarly journals On the Effects of Dissipative Turbulence on the Narrow Emission‐Line Ratios in Seyfert Galaxies

2007 ◽  
Vol 668 (2) ◽  
pp. 730-737 ◽  
Author(s):  
S. B. Kraemer ◽  
M. C. Bottorff ◽  
D. M. Crenshaw
Keyword(s):  
Emission Line ◽  
Seyfert Galaxies ◽  
Dissipative Turbulence ◽  
Narrow Emission

scholarly journals Velocity Offsets Due to Mass Outflows in Active Galaxies

2009 ◽  
Vol 5 (S267) ◽  
pp. 387-392
Author(s):  
D. M. Crenshaw ◽  
S. B. Kraemer ◽  
H. R. Schmitt ◽  
R. F. Mushotzky ◽  
J. P. Dunn
Keyword(s):  
Seyfert Galaxies ◽  
Emission Lines ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Ionized Gas ◽  
Ngc 4151 ◽  
Spatially Resolved ◽  
Mass Outflow ◽  
Ngc 1068 ◽  
Narrow Emission

AbstractWe present a study of the radial velocity offsets between AGN-related narrow emission lines and host-galaxy emission and absorption lines in Seyfert galaxies with observed redshifts less than 0.043. We find that 35% of the Seyferts in the sample show [O iii] emission lines with blueshifts with respect to their host galaxies exceeding 50 km s−1, whereas only 6% show redshifts this large, in qualitative agreement with most previous studies. We also find that a greater percentage of Seyfert 1 galaxies show blueshifts than Seyfert 2 galaxies. Using HST/STIS spatially-resolved spectra of the Seyfert 2 galaxy NGC 1068 and the Seyfert 1 galaxy NGC 4151, we generate geometric models of their narrow-line regions (NLRs) and inner galactic disks and show how these models can explain the blueshifted [O iii] emission lines in collapsed STIS spectra of these two Seyferts. We conclude that the combination of mass outflow of ionized gas in the NLR and extinction by dust in the inner disk (primarily in the form of dust spirals) is primarily responsible for the velocity offsets in Seyfert galaxies.

scholarly journals Radio Nuclei in Nearby Galaxies

1984 ◽  
Vol 110 ◽  
pp. 251-256
Author(s):  
E. Preuss
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Instrumental Performance ◽  
Nuclear Activity ◽  
Normal Galaxies ◽  
Nearby Galaxies ◽  
The Subject ◽  
5 Ghz ◽  
Work Done

This review is an attempt to summarize VLBI continuum observations at cm- and dm-wavelengths of active galactic nuclei at distances ≲ 100 Mpc (Ho = 50 km s−1 Mpc−1). ‘Nearby galaxies’, thus defined, are close enough for achieving the highest possible spatial resolution. Galaxies at these distances, however, typically do not show extreme and rare forms of nuclear activity such as powerful radio sources, the cores of which are relatively easy to map with VLBI, and which are therefore the subject of most of the VLBI work done so far (see e.g. Preuss, 1983). Nearby active galaxies show rather more ‘ordinary’ forms of nuclear activity; they include a few of the weaker classical ‘radio galaxies’, but most of them are Seyfert galaxies and mildly active ‘normal galaxies’. Their total radio emission is typically weak (P(5 GHz) ≲ 1031 erg s−1 Hz−1) and so are their compact radio nuclei (if any). The highest available sensitivity is therefore required for their study and the current instrumental performance is just becoming sufficient to tackle the strongest of them in the hope of obtaining maps.

scholarly journals Nuclear Activity in the Hickson Compact Groups of Galaxies

1999 ◽  
Vol 186 ◽  
pp. 418-418
Author(s):  
M. Shimada ◽  
S. Nishiura ◽  
Y. Ohyama ◽  
T. Murayama ◽  
Y. Taniguchi
Keyword(s):  
Emission Line ◽  
The Other ◽  
Compact Groups ◽  
Early Type ◽  
Late Type ◽  
No Emission ◽  
Nuclear Activity ◽  
Groups Of Galaxies ◽  
Nearby Galaxies ◽  
Hickson Compact Groups

In order to study environmental effects on the nuclear activity in galaxies, we have been conducting a spectroscopic study of Hickson Compact Groups of galaxies (HCGs, Hickson 1982) which are the densest agglomeration of galaxies. We obtained nuclear spectra of 62 galaxies in 29 HCGs in the spectral range 6200–7000Å with the 188cm telescope at Okayama Astrophysical Observatory. These spectra were classified into the three types by using the emission line ratio [NII]λ6583/Hα; (1) AGN: [NII]λ6583/Hα >0.6, (2) HII nuclei: [NII]λ6583/Hα <0.6, and (3) Absorption: no emission line. We compared the nuclear activity of galaxies in HCGs with that of nearby galaxies (Ho 1996; Ho, Filippenko & Sargent 1997) which provides a representative sample of field galaxies. In early-type spirals (Sa-Sbc), the fraction of HII nuclei in HCGs is smaller than that in the field galaxies, while the fraction of absorption in HCGs is larger than that in field galaxies. On the other hand, in early-type galaxies (E-S0a) and late-type spirals (Sc-P), we found little difference in the nuclear activity between HCGs and field galaxies.

A Near‐Infrared Imaging Study of Seyfert Galaxies with Extended Emission‐Line Regions

1998 ◽  
Vol 495 (1) ◽  
pp. 196-221 ◽  
Author(s):  
Almudena Alonso‐Herrero ◽  
Chris Simpson ◽  
Martin J. Ward ◽  
Andrew S. Wilson
Keyword(s):  
Emission Line ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Imaging Study ◽  
Seyfert Galaxies ◽  
Near Infrared Imaging ◽  
Extended Emission

scholarly journals An [O iii] search for extended emission around AGN with H i mapping: a distant cloud ionized by Mkn 1

2020 ◽  
Vol 496 (2) ◽  
pp. 1035-1050 ◽  
Author(s):  
Erin Darnell Knese ◽  
William C Keel ◽  
Greg Knese ◽  
Vardha N Bennert ◽  
Alexei Moiseev ◽  
...  
Keyword(s):  
Emission Line ◽  
Optical Spectroscopy ◽  
Large Fraction ◽  
Seyfert Galaxies ◽  
Emission Feature ◽  
Opening Angle ◽  
Entire Sample ◽  
Spatially Extended ◽  
Extended Emission

ABSTRACT Motivated by the discovery of large ionized clouds around AGN, and particularly the large fraction of those that are consistent with photoionized gaseous tidal debris, we searched for [O iii] emission around Seyfert galaxies previously mapped in H i, many with extended gas features. Of 26 Seyfert galaxies, we find one spatially extended emission feature, a discrete cloud projected ≈12 kpc SW from the centre of Mkn 1 and spanning a transverse extent of 8 kpc. Optical spectroscopy (Kast/Lick and SCORPIO/BTA) of this cloud confirms its association with the Mkn 1–NGC 451 galaxy pair, closely matching the kinematics of nearby H i structures, and reveals emission-line ratios requiring photoionization by the AGN at roughly the direct observed luminosity of the nucleus. For the entire sample, the full opening angle of the ionization cones (bicones) must be &lt;20° if the AGNs are continuously bright for scales longer than the light-traveltimes to the H i structures. Since typical AGN ionization cones are observed to be much broader than this, our low detection fraction may add to evidence for the ubiquity of strong variations in AGN luminosity on scales 104–105 yr.

Outflow signatures in Gemini GMOS-IFU observations of 5 nearby Seyfert 2 galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 274-276
Author(s):  
Izabel C. Freitas ◽  
Rogemar A. Riffel ◽  
Thaisa Storchi-Bergmann
Keyword(s):  
Emission Line ◽  
Spatial Resolution ◽  
Seyfert Galaxies ◽  
Line Flux ◽  
Gas Kinematics ◽  
Field Unit ◽  
Integral Field

AbstractWe use Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) observations of a sample of 5 bright nearby Seyfert galaxies to map their emission-line flux distributions and kinematics at a spatial resolution ranging from 110 to 280 pc. For all galaxies, the gas kinematics show two components: a rotation and an outflow component.

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