scholarly journals On the magnetic energy density in the X-ray emission region of Active Galactic Nuclei

1991 ◽  
Vol 251 (3) ◽  
pp. 529-540 ◽  
Author(s):  
A. Celotti ◽  
G. Ghisellini ◽  
A. C. Fabian
Keyword(s):  
Energy Density ◽  
Active Galactic Nuclei ◽  
Magnetic Energy ◽  
Galactic Nuclei ◽  
Emission Region ◽  
X Ray ◽  
Magnetic Energy Density

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 Can the Local Bubble explain the radio background?

2021 ◽  
Vol 502 (2) ◽  
pp. 2807-2814
Author(s):  
Martin G H Krause ◽  
Martin J Hardcastle
Keyword(s):  
Magnetic Field ◽  
Energy Density ◽  
Radio Emission ◽  
Magnetic Energy ◽  
Cosmic Ray ◽  
Observational Constraints ◽  
Local Bubble ◽  
Magnetic Energy Density ◽  
Magnetic Field Model ◽  
Radio Background

ABSTRACT The ARCADE 2 balloon bolometer along with a number of other instruments have detected what appears to be a radio synchrotron background at frequencies below about 3 GHz. Neither extragalactic radio sources nor diffuse Galactic emission can currently account for this finding. We use the locally measured cosmic ray electron population, demodulated for effects of the Solar wind, and other observational constraints combined with a turbulent magnetic field model to predict the radio synchrotron emission for the Local Bubble. We find that the spectral index of the modelled radio emission is roughly consistent with the radio background. Our model can approximately reproduce the observed antenna temperatures for a mean magnetic field strength B between 3 and 5 nT. We argue that this would not violate observational constraints from pulsar measurements. However, the curvature in the predicted spectrum would mean that other, so far unknown sources would have to contribute below 100 MHz. Also, the magnetic energy density would then dominate over thermal and cosmic ray electron energy density, likely causing an inverse magnetic cascade with large variations of the radio emission in different sky directions as well as high polarization. We argue that this disagrees with several observations and thus that the magnetic field is probably much lower, quite possibly limited by equipartition with the energy density in relativistic or thermal particles (B = 0.2−0.6 nT). In the latter case, we predict a contribution of the Local Bubble to the unexplained radio background at most at the per cent level.

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.

scholarly journals Hot gaseous atmospheres of rotating galaxies observed with XMM–Newton

2020 ◽  
Vol 499 (4) ◽  
pp. 5163-5174
Author(s):  
A Juráňová ◽  
N Werner ◽  
P E J Nulsen ◽  
M Gaspari ◽  
K Lakhchaura ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Active Galactic Nuclei ◽  
Spiral Galaxy ◽  
Galactic Nuclei ◽  
X Ray ◽  
Hot Gas ◽  
Heating And Cooling ◽  
Theoretical Predictions ◽  
Central Regions ◽  
Gaseous Atmospheres

ABSTRACT X-ray emitting atmospheres of non-rotating early-type galaxies and their connection to central active galactic nuclei have been thoroughly studied over the years. However, in systems with significant angular momentum, processes of heating and cooling are likely to proceed differently. We present an analysis of the hot atmospheres of six lenticulars and a spiral galaxy to study the effects of angular momentum on the hot gas properties. We find an alignment between the hot gas and the stellar distribution, with the ellipticity of the X-ray emission generally lower than that of the optical stellar emission, consistent with theoretical predictions for rotationally supported hot atmospheres. The entropy profiles of NGC 4382 and the massive spiral galaxy NGC 1961 are significantly shallower than the entropy distribution in other galaxies, suggesting the presence of strong heating (via outflows or compressional) in the central regions of these systems. Finally, we investigate the thermal (in)stability of the hot atmospheres via criteria such as the TI- and C-ratio, and discuss the possibility that the discs of cold gas present in these objects have condensed out of the hot atmospheres.

scholarly journals The X‐Ray Properties of Active Galactic Nuclei with Double‐peaked Balmer Lines

2006 ◽  
Vol 651 (2) ◽  
pp. 749-766 ◽  
Author(s):  
Iskra V. Strateva ◽  
W. N. Brandt ◽  
Michael Eracleous ◽  
Donald P. Schneider ◽  
George Chartas
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
Balmer Lines

scholarly journals Luminosity-dependent unification of active galactic nuclei and the X-ray Baldwin effect

2013 ◽  
Vol 553 ◽  
pp. A29 ◽  
Author(s):  
C. Ricci ◽  
S. Paltani ◽  
H. Awaki ◽  
P.-O. Petrucci ◽  
Y. Ueda ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Baldwin Effect ◽  
X Ray

Central Black Hole Masses in Active Galactic Nuclei Inferred from X‐Ray Variability

1998 ◽  
Vol 500 (2) ◽  
pp. 642-659 ◽  
Author(s):  
Kiyoshi Hayashida ◽  
Sigenori Miyamoto ◽  
Shunji Kitamoto ◽  
Hitoshi Negoro ◽  
Hajime Inoue
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Central Black Hole ◽  
X Ray ◽  
Black Hole Masses

scholarly journals OPTICAL SPECTRAL PROPERTIES OFSWIFTBURST ALERT TELESCOPE HARD X-RAY-SELECTED ACTIVE GALACTIC NUCLEI SOURCES

2010 ◽  
Vol 710 (1) ◽  
pp. 503-539 ◽  
Author(s):  
Lisa M. Winter ◽  
Karen T. Lewis ◽  
Michael Koss ◽  
Sylvain Veilleux ◽  
Brian Keeney ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
X Ray
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