翻訳と辞書 Words near each other ・ Active Disassembly ・ Active disturbance rejection control ・ Active duty ・ Active Duty (album) ・ Active Duty (web site) ・ Active electronically scanned array ・ Active EMI reduction ・ Active Enterprises ・ Active Exploits ・ Active fault ・ Active filter ・ Active fire protection ・ Active Format Description ・ Active fuel length ・ Active Fuel Management ・ Active galactic nucleus ・ Active Gaming Media ・ Active gross rating point ・ Active Guard Reserve ・ Active hard-drive protection ・ Active heave compensation ・ Active hexose correlated compound ・ Active imagination ・ Active immunization ・ Active immunotherapy ・ Active ingredient ・ Active intellect ・ Active Interest Media ・ Active Islamic Youth ・ Active Kidz Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Active galactic nucleus ： ウィキペディア英語版 Active galactic nucleus An active galactic nucleus (AGN) is a compact region at the centre of a galaxy that has a much higher than normal luminosity over at least some portion – and possibly all – of the electromagnetic spectrum. Such excess emission has been observed in the radio, microwaves, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy. The radiation from an AGN is believed to be a result of accretion of mass by a supermassive black hole at the centre of its host galaxy. AGN are the most luminous persistent sources of electromagnetic radiation in the universe, and as such can be used as a means of discovering distant objects; their evolution as a function of cosmic time also puts constraints on models of the cosmos. ==Models of the active nucleus== For a long time it has been argued that an AGN must be powered by accretion of mass onto massive black holes (106 to 1010 times the Solar mass). AGN are both compact and persistently extremely luminous. Accretion can potentially give very efficient conversion of potential and kinetic energy to radiation, and a massive black hole has a high Eddington luminosity, and as a result, it can provide the observed high persistent luminosity. Supermassive black holes are now believed to exist in the centres of most if not all massive galaxies since the mass of the black hole correlates well with the velocity dispersion of the galactic bulge (the M-sigma relation) or with bulge luminosity. Thus AGN-like characteristics are expected whenever a supply of material for accretion comes within the sphere of influence of the central black hole. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Active galactic nucleus」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.