منابع مشابه
NGC 4151 – A unified active galactic nucleus
We present a unified picture of active galactic nuclei which we construct from a detailed model of line emission in the active source in NGC 4151. This source provides us with an opportunity to explore the variation of structure with luminosity in an object which, in the model, derives its unusual properties as a consequence of the angle of the accretion disc to the line of sight. The key featu...
متن کاملActive Galactic Nucleus Emission-line Properties versus the Eddington Ratio
We analyze UV spectra for a large sample of 578 type 1 active galactic nuclei and derive Eddington ratios, L=LEdd, from the bolometric luminosities and emission-line widths for each object in the sample. The sample spans 5 orders of magnitude in supermassive black hole (SMBH) mass, 7 orders of magnitude in luminosity, and a redshift range 0 z 5. We include a sample of 26 low-redshift narrow-lin...
متن کاملFactors Determining Variability Time in Active Galactic Nucleus Jets
The relationship between observed variability time and emission region geometry is explored for the case of emission by relativistic jets. The approximate formula for the jet-frame size of the emission region, R = Dc∆tobs is shown to lead to large systematic errors when used together with observed luminosity and assumed or estimated Doppler factor D to estimate the jet-frame photon energy densi...
متن کاملAnisotropic X-ray emission in active galactic nucleus accretion discs
Straightforward models of X-ray reflection in the inner region of accretion discs predict that the primary X-ray flux and the flux reflected off the surface of the disc should vary together, albeit with a short light traveltime delay. Most of the observations, however, show that the X-ray flux can vary while the reflected features remain constant. Here we propose a simple explanation for this. ...
متن کاملActive galactic nucleus feedback in clusters of galaxies.
Observations made during the last ten years with the Chandra X-ray Observatory have shed much light on the cooling gas in the centers of clusters of galaxies and the role of active galactic nucleus (AGN) heating. Cooling of the hot intracluster medium in cluster centers can feed the supermassive black holes found in the nuclei of the dominant cluster galaxies leading to AGN outbursts which can ...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1985
ISSN: 0074-1809
DOI: 10.1017/s0074180900242770