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AGN Luminosity Function as f(z)
Hello,
I've so far not found any values for numbers of active galaxies vs normal galaxies across time. What percentage of galaxies go through an active phase? I would expect that most galaxies would go through an active phase due to mergers that spin up the angular momentum in the central region of the combined galaxy. But I'm looking for any estimates for percentage of galaxies that go through an active phase during their history. Thanks for any direction on existing papers, rt |
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AGN Luminosity Function as f(z)
On Saturday, December 17, 2016 at 10:10:12 AM UTC-5, wrote:
Hello, I've so far not found any values for numbers of active galaxies vs normal galaxies across time. What percentage of galaxies go through an active phase? I would expect that most galaxies would go through an active phase due to mergers that spin up the angular momentum in the central region of the combined galaxy. But I'm looking for any estimates for percentage of galaxies that go through an active phase during their history. Thanks for any direction on existing papers, rt The magic word is "duty cycle". Here are two articles from 2000 that give a good background: "Evolution of QSOs and other Active Nuclei", http://pages.astronomy.ua.edu/keel/g...qsoevolve.html "Fueling the AGN", esp Section 8, https://ned.ipac.caltech.edu/level5/..._contents.html This paper, Shankar+ (2010), arXiv version: https://arxiv.org/abs/1004.1173, shows how much work was done in just a decade; check the papers which cite this for more recent work. Hope this helps. |
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AGN Luminosity Function as f(z)
On Sunday, December 18, 2016 at 1:31:41 PM UTC-8, wrote:
On Saturday, December 17, 2016 at 10:10:12 AM UTC-5, wrote: Jeanta, thanks for these links. Lots to read. Duty cycle makes good sense. It occurs to me that there is a very basic issue I'm not sure I understand. How is z determined for quasars? I assume its from analysis of emission lines rather than absorption lines. Is there a class of quasar where the z value is unknown due to the light being featureless? I guess I'm confused since if the quasar is light from some process around a BH within a galaxy, then I'd expect that light to blind observation of stellar emissions nearby, from which a z value could be attained. Does z come somehow from the continuum from the BH light, or, ???? Thanks again for the references, rt The magic word is "duty cycle". Here are two articles from 2000 that give a good background: "Evolution of QSOs and other Active Nuclei", http://pages.astronomy.ua.edu/keel/g...qsoevolve.html "Fueling the AGN", esp Section 8, https://ned.ipac.caltech.edu/level5/..._contents.html This paper, Shankar+ (2010), arXiv version: https://arxiv.org/abs/1004.1173, shows how much work was done in just a decade; check the papers which cite this for more recent work. Hope this helps. |
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