NGC 4151 and MCG 8-11-11: Two X-Ray Seyfert Galaxies with Strong Soft γ-Ray Emission

1981 ◽  
pp. 107-112
Author(s):  
L. Bassani ◽  
R. C. Butler ◽  
A. J. Dean ◽  
G. Di Cocco ◽  
N. A. Dipper ◽  
...  
Keyword(s):  
Seyfert Galaxies ◽  
X Ray ◽  
Ngc 4151 ◽  
Γ Ray

Extended soft X-ray emission in Seyfert galaxies: ROSAT HRI observations of NGC 3516, NGC 4151, and Markarian 3

1995 ◽  
Vol 439 ◽  
pp. 121 ◽  
Author(s):  
Jon A. Morse ◽  
Andrew S. Wilson ◽  
Martin Elvis ◽  
Kimberly A. Weaver
Keyword(s):  
Seyfert Galaxies ◽  
X Ray ◽  
Ngc 4151

scholarly journals X-Ray Properties of Galactic Nuclei

1980 ◽  
Vol 5 ◽  
pp. 623-630
Author(s):  
Daniel W. Weedman
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Seyfert Galaxies ◽  
Strong Emission ◽  
X Ray ◽  
Ngc 4151 ◽  
Survey Results ◽  
Emission Line Galaxies

Preparing this review was my just punishment for stating only two years ago - in another review (Weedman 1977) - that Seyfert galaxies are not strong X-ray sources. I said that because, as recently as three years ago, NGC 4151 was the only Seyfert galaxy known as an X-ray source. Now we have 36 Seyfert 1 galaxies, along with 12 other galaxies with strong emission-line nuclei, that are X-ray sources. And this is all without even having HEAO-2 data at our disposal yet. The study of active galactic nuclei with X-ray astronomy is progressing so rapidly that a reviewer feels almost hopeless. The best I can do is summarize what is known as of the summer of 1979 and give a simple overview of how X-ray and other properties relate.Some excellent reviews of the X-ray properties of Seyfert and other emission-line galaxies already exist. I especially recommend that by Andrew Wilson (1979). He provides very complete references as of a year ago, but X-ray astronomy is progressing so rapidly that he then had only somewhat more than half the active nuclei now in Tables 1 and 2. It was the group working with the Ariel V SSI that made the initial comprehensive X-ray studies of Seyfert galaxies (Ward et al. 1977, Elvis et al. 1978). The UHURU results for Seyfert galaxies followed soon after and are summarized by Tananbaum et al. (1978); the HEAO-A-2 survey results are now in press (Marshall et al. 1979) I have tried to incorporate these and other recent results in Tables 1 and 2.

NGC 4151 and MCG 8-11-11: Two X-ray seyfert galaxies with strong soft ?-ray emission

1981 ◽  
Vol 30 (1-4) ◽  
pp. 107-112 ◽  
Author(s):  
L. Bassani ◽  
R. C. Butler ◽  
A. J. Dean ◽  
G. Di Cocco ◽  
N. A. Dipper ◽  
...  
Keyword(s):  
Seyfert Galaxies ◽  
X Ray ◽  
Ngc 4151

scholarly journals Rapid Continuum Variability in NGC 4151

1997 ◽  
Vol 159 ◽  
pp. 78-79
Author(s):  
Rick Edelson
Keyword(s):  
X Rays ◽  
Medium Energy ◽  
X Ray ◽  
Ngc 4151 ◽  
Significant Variability ◽  
Optical Wavelengths ◽  
Γ Ray

The bright Seyfert 1 galaxy NGC 4151 was monitored intensively by IUE, ROSAT, ASCA, CGRO, and ground-based telescopes for 10 days in 1993 December. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical wavelengths (see Fig. la). The strongest variations were seen in medium energy (~1.5keV) X-rays, with a normalized variability amplitude (NVA) of 24%. Weaker (NVA = 6%) variations, uncorrelated with those at lower energies, were seen at soft γ-ray energies of ~100keV. No significant variability was seen in softer (0.1–1 keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased within increasing wavelength, from 9% to 1% between 1275 Å and 6900 Å.

scholarly journals Active Nuclei and Redshift Problems

1983 ◽  
Vol 6 ◽  
pp. 531-533
Author(s):  
Geoffrey Burbidge
Keyword(s):  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Radio Sources ◽  
Powerful Radio ◽  
Radiation Mechanism ◽  
X Ray ◽  
Major Interest ◽  
Relativistic Particles

More than 20 years ago V. A. Ambartsumian proposed that much of the activity in galaxies was dominated and even generated by their nuclei. Subsequent observational work in radio, optical and x-ray frequencies has borne out his prophecy, and major interest has centered about the nature of the machine in the galactic nucleus. The major characteristic of this machine is that it releases energy rapidly and often spasmodically by processes which are not thermonuclear in origin.The original studies which led to the conclusion that nuclei were all important were observations of the powerful radio sources and Seyfert galaxies, and evidence for the ejection of gas from galaxies of many types. The realization that the synchrotron mechanism was the dominant radiation mechanism and the later studies of Compton radiation were fundamental in leading to the conclusion that large fluxes of relativistic particles must be generated in galactic nuclei.

scholarly journals A comprehensive analysis of the hard X-ray spectra of bright Seyfert galaxies

2016 ◽  
Vol 458 (3) ◽  
pp. 2454-2475 ◽  
Author(s):  
P. Lubiński ◽  
V. Beckmann ◽  
L. Gibaud ◽  
S. Paltani ◽  
I. E. Papadakis ◽  
...  
Keyword(s):  
Seyfert Galaxies ◽  
Comprehensive Analysis ◽  
X Ray

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.

scholarly journals The Balmer lines in the Seyfert Galaxies NGC 5548 and NGC 4151

1972 ◽  
Vol 44 ◽  
pp. 155-159
Author(s):  
R. Weymann ◽  
R. Cromwell
Keyword(s):  
Electron Scattering ◽  
Small Volume ◽  
Seyfert Galaxies ◽  
Ngc 4151 ◽  
Transient Nature ◽  
Balmer Lines ◽  
Ngc 5548

The profiles of the Balmer lines in NGC 5548 as reported by Dibai et al. (1968) were somewhat asymmetric, whereas those reported by Anderson (1970) are smooth and symmetric. We present profiles which are strongly asymmetric, resembling those of Dibai et al. Evidently electron scattering is not the sole principal broadening agent and we must deal with velocities ∼ 2500 km s−1 in a very small volume.The transient nature of the P-Cygni type profiles in the Balmer lines of NGC 4151 has previously been noted (Cromwell and Weymann, 1970). These lines have since disappeared, at the resolution available to us, in a time of 3 months. A model in which frequent outbursts of shells or filaments produce transient features in the Balmer lines, while the accumulated material from past outbursts produces the relatively stable HeI λ 3889 feature, seems the most plausible.

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