Results 21 to 30 of about 63,914 (268)
The Astrophysical Journal, 2023 Above ∼3 keV, the X-ray spectrum of active galactic nuclei (AGNs) is characterized by the intrinsic continuum and Compton reflection features. For type-1 AGNs, several regions may contribute to the reflection.
César Ivan Victoria-Ceballos +5 more
doaj +1 more source
Confrontation of Observation and Theory: High-frequency QPOs in X-Ray Binaries, Tidal Disruption Events, and Active Galactic Nuclei [PDF]
, 2020 We compile observations of high-frequency quasi-periodic oscillations (QPOs) around black holes, both stellar and supermassive, and compare their positions in the parameter space of black hole mass, spin, and oscillation frequency.
K. Smith, Celia R. Tandon, R. Wagoner
semanticscholar +1 more source
Local supermassive black holes, relics of active galactic nuclei and the X-ray background [PDF]
, 2003 We quantify the importance of mass accretion during AGN phases in the growth of supermassive black holes (BH) by comparing the mass function of black holes in the local universe with that expected from AGN relics, which are black holes grown entirely ...
A. Marconi +5 more
semanticscholar +1 more source
X-Rays from Active Galactic Nuclei [PDF]
Highlights of Astronomy, 1983 Recent X-ray observations of active galactic nuclei and Seyfert galaxies in particular are briefly reviewed. The application of the efficiency limit to rapidly varying luminous sources such as NGC 6814 is discussed. It is argued that the variability and probable MeV spectral turnover imply that most of the electrons which radiate the observed flux are ...
openaire +1 more source
The Astrophysical Journal, 2023 To understand the formation and growth of supermassive black holes (SMBHs) and their coevolution with host galaxies, it is essential to know the impact of environment on the activity of active galactic nuclei (AGNs).
Zhensong Hu +16 more
doaj +1 more source
X‐ray active galactic nuclei in the core of the Perseus cluster [PDF]
, 2007 We present a study of the X-ray emission from the nuclei of galaxies observed in the core of the Perseus cluster in a deep exposure with Chandra. Point sources are found coincident with the nuclei of 13 early-type galaxies, as well as the central galaxy ...
S. Santra, Jeremy S. Sanders, A. Fabian
semanticscholar +1 more source
X-rays from active galactic nuclei
The Astrophysical Journal, 1981 Through detailed numerical calculations, we have shown that production of thermal photons at the self-absorbed cyclotron higher harmonics and Comptonization of those soft photons in a hot plasma with the electron temperature 10/sup 9/ K provide a natural mechanism to account for the dominant observed features of the X-ray emission in the active ...
F. Takahara, S. Tsuruta, S. Ichimaru
openaire +1 more source
Sources of X-rays from galaxies [PDF]
, 2011 Galactic X-ray emission is a manifestation of various high-energy phenomena and processes. The brightest X-ray sources are typically accretion-powered objects: active galactic nuclei and low- or high-mass X-ray binaries.
Liu +10 more
core +1 more source
X-ray spectral and eclipsing model of the clumpy obscurer in active galactic nuclei [PDF]
Astronomy & Astrophysics, 2019 We present a unification model for a clumpy obscurer in active galactic nuclei (AGN) and investigate the properties of the resulting X-ray spectrum. Our model is constructed to reproduce the column density distribution of the AGN population and cloud ...
J. Buchner +4 more
semanticscholar +1 more source
What obscures low-X-ray-scattering active galactic nuclei?★ [PDF]
Monthly Notices of the Royal Astronomical Society, 2013 10 pages, 5 figures, 2 tables; accepted for publication in ...
Hönig, Sebastian Florian +6 more
openaire +3 more sources