scholarly journals Exploring the Inner Narrow-Line Regions of Seyfert Galaxies

2009 ◽  
Vol 5 (S267) ◽  
pp. 401-401
Author(s):  
S. B. Kraemer ◽  
D. M. Crenshaw ◽  
M. L. Trippe ◽  
H. R. Schmitt ◽  
M. Meléndez
Keyword(s):  
Emission Line ◽  
Seyfert Galaxies ◽  
Uv Spectra ◽  
Narrow Line ◽  
Ngc 4151 ◽  
Radial Extent ◽  
Wide Range ◽  
Heterogeneous Nature ◽  
Mass Outflow ◽  
Ngc 1068

In HST/STIS optical spectra of Seyfert galaxies, there is often a bright knot of [O iii] emission in the inner NLR. In the case of the Seyfert 1 galaxy NGC 4151, we have shown that the emission-line gas may be associated with the mass outflow detected in absorption in UV spectra, which suggests that we are probing regions close to the AGN. Here we present results for the luminous Seyfert 2 galaxy Mrk 573. The spectra reveal the presence of lines from a wide range of ionization states (see Figure 1), which is indicative of the heterogeneous nature of the emission-line gas. As in our studies of other Seyfert galaxies, including NGC 1068, NGC 4151, and Mrk 3, there is evidence for emission from low-ionization gas outside the nominal emission-line bicone. Finally, based on photoionization modeling, we find that the central emission-line knot in Mrk 573 is some tens of parsecs from the AGN, similar to other Seyfert 2 galaxies, which suggests that the material that is obscuring the central AGN in Seyfert 2s must have a similar radial extent.

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 Mass outflow of the X-ray emission line gas in NGC 4151

2020 ◽  
Vol 15 (S359) ◽  
pp. 131-135
Author(s):  
S. B. Kraemer ◽  
T. J. Turner ◽  
D. M. Crenshaw ◽  
H. R. Schmitt ◽  
M. Revalski ◽  
...  
Keyword(s):  
Emission Line ◽  
Total Mass ◽  
High Energy ◽  
Model Parameters ◽  
Zeroth Order ◽  
Space Telescope ◽  
X Ray ◽  
Ngc 4151 ◽  
Outflow Rate ◽  
Mass Outflow

AbstractWe have analyzed Chandra/High Energy Transmission Grating spectra of the X-ray emission line gas in the Seyfert galaxy NGC 4151. The zeroth-order spectral images show extended H- and He-like O and Ne, up to a distance r ˜ 200 pc from the nucleus. Using the 1st-order spectra, we measure an average line velocity ˜230 km s–1, suggesting significant outflow of X-ray gas. We generated Cloudy photoionization models to fit the 1st-order spectra; the fit required three distinct emission-line components. To estimate the total mass of ionized gas (M) and the mass outflow rates, we applied the model parameters to fit the zeroth-order emission-line profiles of Ne IX and Ne X. We determined an M ≍ 5.4 × 105Mʘ. Assuming the same kinematic profile as that for the [O III] gas, derived from our analysis of Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra, the peak X-ray mass outflow rate is approximately 1.8 Mʘ yr–1, at r ˜ 150 pc. The total mass and mass outflow rates are similar to those determined using [O III], implying that the X-ray gas is a major outflow component. However, unlike the optical outflows, the X-ray emitting mass outflow rate does not drop off at r > 100pc, which suggests that it may have a greater impact on the host galaxy.

A Study of the Seyfert Galaxy NGC 4151

1967 ◽  
Vol 1 (1) ◽  
pp. 7-7 ◽  
Author(s):  
J. B. Oke ◽  
Wallace L. W. Sargent
Keyword(s):  
Continuous Spectrum ◽  
Seyfert Galaxy ◽  
Seyfert Galaxies ◽  
Radio Galaxies ◽  
Emission Lines ◽  
Ngc 4151 ◽  
Broad Emission ◽  
Ngc 1068 ◽  
Stellar Sources ◽  
No Absorption

The small group of known Seyfert galaxies (Seyfert 1943) is of interest because it is clear that some violent activity is occurring in the nucleus, and some of the properties suggest a relationship with quasi-stellar sources. The spectrum of a Seyfert galaxy consists of strong, often very broad, emission lines superposed on a continuous spectrum which in some cases shows no absorption-line features. Two of the galaxies, NGC 1068 and 1275, are radio galaxies and the latter is known to be variable at radio frequencies (Dent 1966).

scholarly journals Survey of Milliarcsec Structure in Eight Seyfert Galaxies: Results on NGC 1068 and NGC 4151

1998 ◽  
Vol 164 ◽  
pp. 301-302 ◽  
Author(s):  
A. L. Roy ◽  
J. S. Ulvestad ◽  
E. J. M. Colbert ◽  
A. S. Wilson ◽  
R. P. Norris
Keyword(s):  
Spectral Index ◽  
Low Frequency ◽  
Seyfert Galaxies ◽  
Scale Structure ◽  
Scale Morphology ◽  
Ngc 4151 ◽  
Ngc 1068

AbstractWe are surveying eight nearby Seyfert galaxies (four Sy1s and four Sy2s) that have compact radio cores, using the VLBA. We are interested in parsec-scale morphology and low-frequency absorption effects, and so are observing four frequencies (1.6, 4.8, 8.4 and 15 GHz) to get spectral-index diagnostics. In this paper, we present results on two galaxies, NGC 1068 and NGC 4151. NGC 4151 shows a curved radio jet on the sub-parsec scale, with the smallest scale structure misaligned by 55° from the jet on scales of parsecs to hundreds of parsecs. NGC 1068 contains several components in the inner tens of parsecs, with those components showing a variety of absorption and resolution effects.

scholarly journals Radio Observations of Neutral Hydrogen in Four Seyfert Galaxies

1972 ◽  
Vol 44 ◽  
pp. 269-270
Author(s):  
Ronald J. Allen ◽  
Bernard F. Darchy ◽  
Robert Lauqué
Keyword(s):  
Total Mass ◽  
Large Scale ◽  
Neutral Hydrogen ◽  
Seyfert Galaxies ◽  
Optical Spectra ◽  
Optical Data ◽  
Ngc 4151 ◽  
Ngc 1068 ◽  
Ngc 4051 ◽  
Radial Outflow

The 21-cm wavelength radiation from neutral hydrogen in NGC 1068, NGC 3227, NGC 4051 and NGC 4151 has been observed with the large radio telescope at Nanĉay, France. Since the angular sizes of these galaxies are of the same order as the telescope right ascension beam-width, no information on the angular distribution of the neutral hydrogen was obtained. However the radial velocity distribution of the total hydrogen (the ‘integrated profile’) of the whole galaxy was measured for each of the four galaxies. The hydrogen masses and total masses can be calculated from these profiles using simple models of galaxy shapes and rotation curves.Optical spectra sometimes show evidence for explosive phenomena and radial outflow of gas in the central regions of Seyfert galaxies. We have examined the integrated radio profiles for indications of large-scale radial motions of neutral hydrogen in two ways. First, for all four galaxies observed, we compare the ratios of hydrogen mass to total mass with the values obtained from other galaxies (not Seyfert) of the same morphological type. Second, for these galaxies where the optical data are available, we compare the estimates of total mass obtained from the optical spectra with the estimates based on the width of the radio profile.We conclude from these comparisons that the integrated profile of NGC 1068 is unusually broad. One possible interpretation which is qualitatively consistent with the optical data is that an appreciable fraction (about ⅓) of the neutral hydrogen content of NGC 1068 is moving radially outward with velocities of about 200 km s−1 An indication of similar phenomena (although less extreme) is obtained for NGC 4051. The widths of the integrated profiles of NGC 3227 and NGC 4151 do not seem unusual.

scholarly journals Emission-Line Asymmetries and the Kinematics of the Narrow-Line Region in AGNs

1989 ◽  
Vol 134 ◽  
pp. 347-348
Author(s):  
Richard A. Shaw ◽  
Michael M. De Robertis
Keyword(s):  
Emission Line ◽  
Fundamental Problem ◽  
Signal To Noise Ratio ◽  
Critical Density ◽  
High Signal ◽  
Symmetric Model ◽  
Narrow Line ◽  
Line Region ◽  
Wide Range ◽  
Narrow Line Region

We have obtained high signal-to-noise ratio CCD spectra at ≤ 150 km/s resolution for 6 high-ionization Seyfert galaxies. We analyzed the profiles of the emission-lines over a wide range in both ionization potential (IP) and critical density (Ncr) in order to study the fundamental problem of cloud motion in the narrow-line region (NLR). Using the known correlations between FWHM and IP and/or Ncr for these galaxies, and assuming that the blueward profile asymmetries result from the combined effects of radially infalling or outflowing clouds and extinction within or between them, we deconvolve these effects by analyzing the correlation between emission-line asymmetries and both IP and Ncr. We find fair to good correlations in the sense that lines with high IP and Ncr also tend to have high asymmetry, while lines with low IP and Ncr have low but usually non-zero asymmetry. Simulated emission-line profiles generated with a spherically-symmetric model of a NLR suggest that the extinction arises primarily within radially infalling clouds.

Photoproduction of gravitational radiation by some astrophysical objects

1976 ◽  
Vol 54 (1) ◽  
pp. 76-79 ◽  
Author(s):  
G. Papini ◽  
S.-R. Valluri
Keyword(s):  
Neutron Stars ◽  
Electromagnetic Fields ◽  
Gravitational Radiation ◽  
Galactic Center ◽  
Seyfert Galaxies ◽  
The Sun ◽  
Ngc 4151 ◽  
Astrophysical Objects ◽  
Ngc 1068

Estimates are given for the amounts of gravitational radiation produced in the interaction of photons with the static electromagnetic fields of some astrophysical objects. These are the Sun, Quasar 3C273, Seyfert galaxies NGC 1068 and NGC 4151, the Galactic Center, and neutron stars.

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