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What are black hole coronas? Are they different from accretion disks? If so, how are they formed?

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  • $\begingroup$ I was really hoping that someone'd enlighten me, did I break any rule? Violate any community standard? Do I need to rephrase my question? Does my question lack anything? I'd really appreciate if someone enlightens me here. $\endgroup$ – Satyajit Sen Dec 3 '15 at 8:00
  • $\begingroup$ On this site, we prefer that each post ask one specific question. This post has seven question marks in it. This prevents people from writing answers, because in order to produce an answer that person has to answer seven things instead of one. It's much better if you would edit this post so that it asks one specific question. It's ok to post multiple specific questions instead of one post with so many questions. $\endgroup$ – DanielSank Dec 3 '15 at 8:11
  • $\begingroup$ Is this better, @DanielSank? $\endgroup$ – Satyajit Sen Dec 3 '15 at 8:19
  • $\begingroup$ That's a huge improvement. I'm sure one of the many expert astrophysicists on the site will answer this for you. Note that it is the middle of the night for many users right now. $\endgroup$ – DanielSank Dec 3 '15 at 8:38
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The corona is the layer above/outside the main accretion disk. Just as with the solar corona, this is the region of extremely diffuse, hot material. It is relatively optically thin (transparent), and it is a source of X-rays due to thermal bremsstrahlung. The idea is that the accretion disk isn't just bordered by complete vacuum; some material is stripped from it, and some electron-positron pairs can be produced by the high-energy photons and strong magnetic fields in the region.

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  • $\begingroup$ So any and all bipolar outflows from a black hole are basically coronal flares in the form of X-rays, right? $\endgroup$ – Satyajit Sen Dec 4 '15 at 13:58
  • $\begingroup$ This is out of this topic, but could you have a look at this which resurfaced due to an inane answer physics.stackexchange.com/questions/192315/… . Is the chosen answer off the mainstream? $\endgroup$ – anna v Jan 7 '16 at 15:40
  • $\begingroup$ @annav I do believe the chosen answer is off the mainstream. The cited paper is not quite wrong, but it uses language from 50 years ago that is misleading when put in a modern context. The only way you get a speed of light that is not $c$ is if you measure distance and time in different reference frames, and there's never a good reason to do that. $\endgroup$ – user10851 Jan 7 '16 at 18:09
  • $\begingroup$ I started interacting with comments with him. thanks for confirming my doubts $\endgroup$ – anna v Jan 7 '16 at 18:10

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