Results 11 to 20 of about 80,758 (270)
Proc Natl Acad Sci U S A, 1999 Active galactic nuclei are the most powerful, long-lived objects in the Universe. Recent data confirm the theoretical idea that the power source is accretion into a massive black hole. The common occurrence of obscuration and outflows probably means that the contribution of active galactic nuclei to the power density of the Universe has been ...
Fabian AC.
europepmc +6 more sources
Fuelling active galactic nuclei [PDF]
Monthly Notices of the Royal Astronomical Society: Letters, 2007 Abstract We suggest that most nearby active galactic nuclei are fed by a series of small-scale, randomly oriented accretion events. Outside a certain radius these events promote rapid star formation, while within it they fuel the supermassive black hole. We show that the events have a characteristic time-evolution.
King, A. R., Pringle, J. E.
openaire +5 more sources
Elusive active galactic nuclei [PDF]
Monthly Notices of the Royal Astronomical Society, 2003 accepted for publication in MNRAS Letters, 6 pages, 3 figures, typos and references ...
R. Maiolino +10 more
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Obscured active galactic nuclei [PDF]
AIP Conference Proceedings, 2001 The properties of the absorption in type 2, narrow line AGNs are reviewed by focusing on the X-ray indicators. I discuss the properties of the cold absorbing medium (the putative torus) and of the reprocessed components, as well as their implications for the unified model.
Maiolino, R.
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Active Galactic Nuclei Search [PDF]
Atoms, 2017 We present the first results of medium-band photometric observations on the 1m Schmidt Telescope of Byurakan Astrophysical Observatory (Armenia). The object sample was created in the SA68 field.
Sergey Kotov, Sergey Dodonov
doaj +2 more sources
, 2010 This work represents the final year project for BSc Physics with Astrophysics degree and it mainly focuses on empirical investigation of the photometry of quasars in the Sloan Digital Sky Survey (SDSS) and the UK Infrared Telescope (UKIRT) Infrared Sky Survey (UKIDSS) systems.
Khassen, Yerbol Farkhatuly
core +4 more sources
X-Ray Eclipses of Active Galactic Nuclei [PDF]
, 2017 X-ray variation is a ubiquitous feature of active galactic nuclei (AGNs), however, its origin is not well understood. In this paper, we show that the X-ray flux variations in some AGNs, and correspondingly the power spectral densities (PSDs) of the ...
Fupeng Zhang, Qingjuan Yu, Youjun Lu
openalex +3 more sources
Unravelling Active Galactic Nuclei [PDF]
, 2000 A complete flat-spectrum radio-loud sample of AGN includes a significant fraction of Seyfert-like AGN including a NLS1. Analysis of their optical spectra suggests that the reddest continuum colours are either associated with AGN in nearby resolved galaxies, or distant quasars showing relatively narrow permitted emission lines.
Oshlack, A. Y. K. N. +5 more
openaire +4 more sources
The Astrophysical Journal, 2023 “Changing-look active galactic nuclei” (CLAGNs) are known to change their apparent types between types 1 and 2, usually accompanied by a drastic change in their luminosity on timescales of years.
Hirofumi Noda +13 more
doaj +1 more source
The Astrophysical Journal, 2023 We report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert galaxy NGC 2992, observed at one of its highest flux levels in the X-rays.
Alfredo Luminari +10 more
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