scholarly journals HIGH-ENERGY EMISSION FROM JET–CLOUD INTERACTIONS IN AGNs

2010 ◽  
Vol 19 (06) ◽  
pp. 931-936 ◽  
Author(s):  
ANABELLA T. ARAUDO ◽  
VALENTÍ BOSCH-RAMON ◽  
GUSTAVO E. ROMERO
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Small Region ◽  
High Energy ◽  
Energy Emission ◽  
Central Regions ◽  
High Energy Emission

Active galactic nuclei present continuum and line emission. The emission lines are originated by gas located close to the central supermassive black hole. Some of these lines are broad, and would be produced in a small region called broad-line region. This region could be formed by clouds surrounding the central black hole. In this work, we study the interaction of such clouds with the base of the jets in active galactic nuclei, and we compute the produced high-energy emission. We focus on sources with low luminosities in the inner jet regions, to avoid strong gamma-ray absorption. We find that the resulting high-energy radiation may be significant in Centaurus A. Also, this phenomenon might be behind the variable gamma-ray emission detected in M87, if very large dark clouds are present. The detection of jet–cloud interactions in active galactic nuclei would give information on the properties of the jet base and the very central regions.

scholarly journals ASCA Observations of Blazars

1998 ◽  
Vol 11 (2) ◽  
pp. 812-815
Author(s):  
T. Takahashi ◽  
H. Kubo ◽  
G. Madejski
Keyword(s):  
Active Galactic Nuclei ◽  
Time Scales ◽  
Small Angle ◽  
Gamma Ray ◽  
Thermal Emission ◽  
Galactic Nuclei ◽  
High Energy ◽  
Energetic Particles ◽  
Energy Emission ◽  
High Energy Emission

During the last years it has become evident that blazar class of AGN emit a lot of energy in the gamma-ray regime. It is generally thought that the non-thermal emission from blazars, observed from radio to GeV/TeV 7-rays, is radiation of very energetic particles via both synchrotron and Compton processes. This underlines the importance of high-energy emission for models of the blazar class of active galactic nuclei. Most of the gamma-bright AGN are variable, and flares with time scales as short as a day have been observed. This suggests that the site of gamma-ray emission is very compact and situated in a fluid which moves relativistically at a small angle towards the observer. It is generally assumed that the emission originates from the jet of these objects.

scholarly journals Radiation from matter entrainment in astrophysical jets: the AGN case

2010 ◽  
Vol 6 (S275) ◽  
pp. 131-135
Author(s):  
A. T. Araudo ◽  
V. Bosch-Ramon ◽  
G. E. Romero
Keyword(s):  
Active Galactic Nuclei ◽  
External Medium ◽  
Galactic Nuclei ◽  
High Energy ◽  
Supersonic Velocity ◽  
Astrophysical Jets ◽  
Energy Emission ◽  
Γ Ray ◽  
High Energy Emission

AbstractJets are found in a variety of astrophysical sources. In all the cases the jet propagates with a supersonic velocity through the external medium, which can be inhomogeneous, and inhomogeneities could penetrate into the jet. The interaction of the jet material with an obstacle produces a bow-like shock within the jet in which particles can be accelerated up to relativistic energies and emit high-energy photons. In this work, we explore the active galactic nuclei scenario, focusing on the dynamical and radiative consequences of the interaction at different jet heights. We find that the produced high-energy emission could be detectable by the current γ-ray telescopes. In general, the jet-clump interactions are a possible mechanism to produce (steady or flaring) high-energy emission in many astrophysical sources in which jets are present.

scholarly journals GAMMA-RAY EMISSION FROM AGNS (SPECIAL FOCUS ON BL LAC OBJECTS)

2010 ◽  
Vol 19 (06) ◽  
pp. 841-848
Author(s):  
F. TAVECCHIO
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Line Of Sight ◽  
Special Focus ◽  
Bl Lac Objects ◽  
Relativistic Jet ◽  
Bl Lac ◽  
High Energy Emission

Blazars, radio-loud active galactic nuclei with the relativistic jet closely aligned with the line of sight, dominate the extragalactic sky observed at gamma-ray energies, above 100 MeV. We discuss some of the emission properties of these sources, focusing in particular on the "blazar sequence" and the interpretative models of the high-energy emission of BL Lac objects.

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 CONSTRAINING THE HIGH-ENERGY EMISSION FROM GAMMA-RAY BURSTS WITHFERMI

2012 ◽  
Vol 754 (2) ◽  
pp. 121 ◽  
Author(s):  
◽  
M. Ackermann ◽  
M. Ajello ◽  
L. Baldini ◽  
G. Barbiellini ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Energy Emission ◽  
High Energy Emission

scholarly journals Upper limits on the high-energy emission from gamma-ray bursts observed by AGILE-GRID

2012 ◽  
Vol 547 ◽  
pp. A95 ◽  
Author(s):  
F. Longo ◽  
E. Moretti ◽  
L. Nava ◽  
R. Desiante ◽  
M. Olivo ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Energy Emission ◽  
Upper Limits ◽  
High Energy Emission
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