scholarly journals Cosmic X-ray Background from Self-absorbed Low Luminosity AGNs

1990 ◽  
Vol 115 ◽  
pp. 276-280
Author(s):  
Jonathan E. Grindlay ◽  
Michael Luke
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
Spectral Shape ◽  
Density Evolution ◽  
Background Spectrum ◽  
Asymptotic Spectrum ◽  
X Ray ◽  
Energy Cutoff ◽  
X Ray Background

AbstractA model is proposed for the origin of the diffuse cosmic x-ray background whereby it is primarily due to the contribution of low luminosity active galactic nuclei which are increasingly self-absorbed at low luminosities. Strong self-absorption for low luminosity objects allows the observed background spectrum to be flatter in the ~2-20 keV band than the asymptotic spectrum, assumed to have mean index γ ~ -0.7 up to a high energy cutoff at ~125 keV. The model can account for the spectral shape and intensity of the background spectrum, as well as its possible fluctuations, if the AGN undergo modest density evolution and the bulk of the CXB arises from AGNs at redshifts z ~ 1-3. The model can be tested with AXAF observations of low luminosity AGNs at 5-10 keV and sensitive new hard x-ray observations.

Radio-loud AGNs with peculiar shape of hard X-ray spectrum: figuring out the reasons

2018 ◽  
Vol 14 (S342) ◽  
pp. 218-219
Author(s):  
E. Fedorova ◽  
B. I. Hnatyk ◽  
V. I. Zhdanov
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
Spectral Shape ◽  
X Ray ◽  
Probable Reason

AbstractWe analyze the hard X-ray properties of five radio-loud active galactic nuclei with peculiar spectral shape. High-energy exponential cut-offs (HEC) in their hard X-ray 3-500 keV spectra are too high for radio loud AGNs (above 100 keV) or even absent.The probable reason of such visible spectral “peculiarity” can be due to the “jet contamination”, i.e we see some mixture of the jet and nuclear emission, but not pure emission of the innermost nucleus. Here we try to estimate the jet and nuclear components of the spectra for a sample of “peculiar” RL AGNs to find out whether these are real or fake features.

scholarly journals NuSTAR Survey of Obscured Swift/BAT-selected Active Galactic Nuclei. II. Median High-energy Cutoff in Seyfert II Hard X-Ray Spectra

2020 ◽  
Vol 905 (1) ◽  
pp. 41
Author(s):  
M. Baloković ◽  
F. A. Harrison ◽  
G. Madejski ◽  
A. Comastri ◽  
C. Ricci ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
X Ray ◽  
Energy Cutoff

scholarly journals NuStar Hard X-Ray View of Low-luminosity Active Galactic Nuclei: High-energy Cutoff and Truncated Thin Disk

2019 ◽  
Vol 870 (2) ◽  
pp. 73 ◽  
Author(s):  
George Younes ◽  
Andrew Ptak ◽  
Luis C. Ho ◽  
Fu-Guo Xie ◽  
Yuichi Terasima ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
Thin Disk ◽  
X Ray ◽  
Energy Cutoff

scholarly journals CAN WE REPRODUCE THE X-RAY BACKGROUND SPECTRAL SHAPE USING LOCAL ACTIVE GALACTIC NUCLEI?

2013 ◽  
Vol 770 (2) ◽  
pp. L37 ◽  
Author(s):  
Ranjan V. Vasudevan ◽  
Richard F. Mushotzky ◽  
Poshak Gandhi
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Spectral Shape ◽  
X Ray ◽  
X Ray Background

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.

Commission N°48: High Energy Astrophysics (Astrophysique Des Hautes Energies)

1988 ◽  
Vol 20 (1) ◽  
pp. 671-675
Author(s):  
C.J. Cesarsky ◽  
R.A. Sunyaev ◽  
G.W. Clark ◽  
R. Giacconi ◽  
Vin-Yue Qu ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Supernova Remnants ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
High Energy ◽  
Clusters Of Galaxies ◽  
High Energy Astrophysics ◽  
X Ray ◽  
X Ray Binaries ◽  
Imaging Telescopes

The european X-ray observatory (EXOSAT), which was launched in 1983 and which finished operations in April 1986, has brought a rich harvest of results in the period 1984-1987, surveyed here. The EXOSAT payload consisted of three sets of instruments: two low energy imaging telescopes (LE:E<2 KeV), a medium-energy experiment (ME:E=l-50KeV) and a gas scintillation proportional counter (GSPC:E=2-20KeV). Over most of the energy range covered, EXOSAT was not more sensitive than its predecessor, the american EINSTEIN satellite. But the EINSTEIN satellite is far from having exhausted the treasures of the X-ray sky. And EXOSAT, thanks to its elliptical 90-hour orbit, had the extra advantage of being able to make long, continuous observations of interesting objects, lasting up to 72 hours. Thus, EXOSAT was very well suited for variability studies, and many of its most important findings are in this area. EXOSAT observations sample a vide range of astrophysical sources: X-ray binaries, cataclysmic variables and active stars; supernova remnants and the interstellar medium; active galactic nuclei, and clusters of galaxies. Among the highlights, let us mention:

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