scholarly journals High-Resolution Observations of the M81 Nucleus

1989 ◽  
Vol 134 ◽  
pp. 513-514
Author(s):  
William C. Keel
Keyword(s):  
High Resolution ◽  
Active Galactic Nuclei ◽  
Radio Source ◽  
Galactic Nuclei ◽  
Line Spectrum ◽  
Narrow Line ◽  
Early Type ◽  
X Ray

The nucleus of the nearby Sb galaxy M81 has been shown to exhibit many of the features prominent in luminous active galactic nuclei: a variable, compact VLBI radio source (Kellermann et al. 1976, Jones, Sramek and Terzian 1981), a central variable X-ray source (Elvis and van Speybroeck 1982, Fabbiano 1988), and broad wings of Balmer emission similar in extent to those typical to Seyfert 1 nuclei (Peimbert and Torres-Peimbert 1981, Shuder and Osterbrock 1981). The nucleus also shows a narrow-line spectrum in many ways typical of LINERs (Heckman 1980), now known to be representative of early-type spiral nuclei in general.

scholarly journals High Resolution X-ray Spectroscopy of Active Galactic Nuclei

1990 ◽  
Vol 115 ◽  
pp. 262-273
Author(s):  
Julian H. Krolik
Keyword(s):  
High Resolution ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Light Sources ◽  
Clusters Of Galaxies ◽  
Relativistic Jets ◽  
Bl Lac Objects ◽  
X Ray ◽  
Interstellar Material ◽  
Scientific Value

AbstractHigh-resolution X-ray spectroscopy has the potential to reveal a number of interesting features of active galactic nuclei, primarily, though not exclusively, through the measurement of absorption lines. After a brief review of the principal problems of AGN research, selected potential high-resolution observations are discussed with a view toward assessing their scientific value and the degree of resolution they will require. Two classes of observations pertaining directly to AGNs are discussed: Fe Kα spectroscopy relevant to the dynamical and thermal character of the emission line zones; and measurement of resonance line absorption by highly-ionized species in BL Lac objects, which should tell us about entrainment of interstellar material by relativistic jets. A third class of potentially important observations uses AGNs as background light sources in order to directly measure the distance to clusters of galaxies.

scholarly journals Swift monitoring and Suzaku spectroscopy of the γ-ray detected narrow-line Seyfert 1 galaxy 1H 0323+342

2014 ◽  
Vol 10 (S312) ◽  
pp. 66-67
Author(s):  
S. Yao ◽  
W. Yuan ◽  
S. Komossa ◽  
D. Grupe ◽  
L. Fuhrmann ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Broad Band ◽  
Galactic Nuclei ◽  
Optical Monitoring ◽  
Narrow Line ◽  
Black Hole Mass ◽  
X Ray ◽  
Small Black Hole ◽  
Special Subset ◽  
Γ Ray

Abstract1H 0323+342 is one of the rare γ-ray detected narrow-line Seyfert 1 galaxies (NLS1s), a special subset of active galactic nuclei (AGN) owing to their hybrid behavior of both NLS1s and blazars. The rarity of such kind of sources makes their properties far from being understood. We analyze simultaneous X-ray and UV/optical monitoring observations of 1H 0323+342 performed by Swift over ~7 years. The UV/X-ray correlation and the broad band SED reveal that the X-ray band is dominated by the disk/corona emission during the observations. The large normalized excess variance of the X-ray variability detected with Suzaku suggests a relatively small black hole mass of the order of 107M⊙, consistent with the estimation based on the broad Hβ line in the optical band.

scholarly journals Blueshifted absorption lines from X-ray reflection in IRAS 13224−3809

2020 ◽  
Vol 493 (2) ◽  
pp. 2518-2522 ◽  
Author(s):  
A C Fabian ◽  
C S Reynolds ◽  
J Jiang ◽  
C Pinto ◽  
L C Gallo ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Power Law ◽  
Galactic Nuclei ◽  
Absorption Lines ◽  
Narrow Line ◽  
X Ray ◽  
Absorbing Layer ◽  
Reflection Component

ABSTRACT We explore a disc origin for the highly blueshifted, variable absorption lines seen in the X-ray spectrum of the narrow-line Seyfert 1 galaxy IRAS 13224−3809. The blueshift corresponds to a velocity of ∼0.25c. Such features in other active galactic nuclei are often interpreted as ultrafast outflows. The velocity is of course present in the orbital motions of the inner disc. The absorption lines in IRAS 13224−3809 are best seen when the flux is low and the reflection component of the disc is strong relative to the power-law continuum. The spectra are consistent with a model in which the reflection component passes through a thin, highly ionized absorbing layer at the surface of the inner disc, the blueshifted side of which dominates the flux due to relativistic aberration (the disc inclination is about 70°). No fast outflow need occurs beyond the disc.

scholarly journals Shocks and Photoionization in the Narrow-Line Region

1997 ◽  
Vol 159 ◽  
pp. 365-377
Author(s):  
Sueli M. Viegas ◽  
Marcella Contini
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Narrow Line ◽  
X Ray ◽  
Physical Conditions ◽  
X Ray Imaging ◽  
Line Region ◽  
Composite Models ◽  
Consistent Picture ◽  
Narrow Line Region

AbstractThe presence of shocked regions in the narrow-line region (NLR) of active galactic nuclei (AGN) is discussed. Their effect on the physical conditions, in addition to photoionization from the central radiation source, is analyzed. We show that composite models, accounting for both shocks and photoionization, provide a consistent picture of the NLR which accounts for the observed emission-line and continuum spectra and is in agreement with the AGN unified model. The study of a particular object, NGC 5252, strengthens these results. It also shows that, besides explaining the observational data, the models make predictions that can be tested by infrared, optical, and X-ray imaging.

scholarly journals Detection of a variable ultrafast outflow in the narrow-line Seyfert 1 galaxy PG 1448+273

2020 ◽  
Vol 495 (4) ◽  
pp. 4769-4781
Author(s):  
P Kosec ◽  
A Zoghbi ◽  
D J Walton ◽  
C Pinto ◽  
A C Fabian ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Spectral Features ◽  
Narrow Line ◽  
X Ray ◽  
Wind Structure ◽  
High Ionization ◽  
Unambiguous Detection ◽  
Absorption Features ◽  
Ionization Parameter

ABSTRACT Relativistically blueshifted absorption features of highly ionized ions, the so-called ultrafast outflows (UFOs), have been detected in the X-ray spectra of a number of accreting supermassive black holes. If these features truly originate from accretion disc winds accelerated to more than 10 per cent of the speed of light, their energy budget is very significant and they can contribute to or even drive galaxy-scale feedback from active galactic nuclei (AGNs). However, the UFO spectral features are often weak due to high ionization of the outflowing material, and the inference of the wind physical properties can be complicated by other spectral features in AGNs such as relativistic reflection. Here we study a highly accreting narrow-line Seyfert 1 galaxy PG 1448+273. We apply an automated, systematic routine for detecting outflows in accreting systems and achieve an unambiguous detection of a UFO in this AGN. The UFO absorption is observed in both soft and hard X-ray bands with the XMM–Newton observatory. The velocity of the outflow is (26 900 ± 600) km s−1 (∼0.09c), with an ionization parameter of $\log (\xi / \textrm {erg~cm~s}^{-1})=4.03_{-0.08}^{+0.10}$ and a column density above 1023 cm−2. At the same time, we detect weak warm absorption features in the spectrum of the object. Our systematic outflow search suggests the presence of further multiphase wind structure, but we cannot claim a significant detection considering the present data quality. The UFO is not detected in a second, shorter observation with XMM–Newton, indicating variability in time, observed also in other similar AGNs.

scholarly journals The correlation of narrow line emission and X-ray luminosity in active galactic nuclei

2006 ◽  
Vol 453 (2) ◽  
pp. 525-533 ◽  
Author(s):  
H. Netzer ◽  
V. Mainieri ◽  
P. Rosati ◽  
B. Trakhtenbrot
Keyword(s):  
Active Galactic Nuclei ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Narrow Line ◽  
X Ray

Polarization Variability of Active Galactic Nuclei and X‐Ray Binaries

1997 ◽  
Vol 487 (1) ◽  
pp. 142-152 ◽  
Author(s):  
Gang Bao ◽  
Petr Hadrava ◽  
Paul J. Wiita ◽  
Ying Xiong
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
X Ray Binaries

scholarly journals Gamma-Ray and Neutrino Signals from Accretion Disk Coronae of Active Galactic Nuclei

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 36
Author(s):  
Yoshiyuki Inoue ◽  
Dmitry Khangulyan ◽  
Akihiro Doi
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Thermal Activity ◽  
X Ray ◽  
Cascade Models ◽  
Coronal Activity ◽  
Ngc 1068 ◽  
High Energy Particles

To explain the X-ray spectra of active galactic nuclei (AGN), non-thermal activity in AGN coronae such as pair cascade models has been extensively discussed in the past literature. Although X-ray and gamma-ray observations in the 1990s disfavored such pair cascade models, recent millimeter-wave observations of nearby Seyferts have established the existence of weak non-thermal coronal activity. In addition, the IceCube collaboration reported NGC 1068, a nearby Seyfert, as the hottest spot in their 10 yr survey. These pieces of evidence are enough to investigate the non-thermal perspective of AGN coronae in depth again. This article summarizes our current observational understanding of AGN coronae and describes how AGN coronae generate high-energy particles. We also provide ways to test the AGN corona model with radio, X-ray, MeV gamma ray, and high-energy neutrino observations.

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