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spaceguy
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06 Apr 2017 21:34

Watsisname wrote:
Not necessarily.  It depends a lot on the magnetic fields in the disk, and the accretion rate.  GRMHD simulations suggest that there can be quite a lot of structure very close to the event horizon:



Ultimately we'll need to wait for the results from EHT to know what's really going on, but the way the disks are currently portrayed in SE is pretty accurate to what we understand so far. :)

Why do quite a bit of accretion disks have giant bulges, often near the outside or inside?
Also could an accretion disk get hot enough for a corona to appear? Also also, how would an astrophysical jet appear with gravitational lensing near the black hole? Sorry for asking questions in the suggestions thread, but no better time than to ask now since I thought of these questions.
 
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Watsisname
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07 Apr 2017 00:37

spaceguy wrote:
Source of the post Why do quite a bit of accretion disks have giant bulges, often near the outside or inside?

I think you're referring to the gravitational lensing effect, which brings the far side of the accretion disk into view.  Let me annotate a screenshot of one with a few explanations and see if that answers your question.
Image

spaceguy wrote:
Source of the post Also could an accretion disk get hot enough for a corona to appear?

Absolutely!  Accretion disks are very hot -- hundreds of thousands to millions of degrees -- and will have a coronal wind of very hot plasma streaming off of them.
spaceguy wrote:
Source of the post Also also, how would an astrophysical jet appear with gravitational lensing near the black hole?

The lensing wont affect its appearance too much -- the more dramatic effect of the lensing is on the appearance of things which are behind the black hole.  The appearance of the jet depends more on the viewer's orientation.  If the jet is aimed somewhat towards you, then you mostly see that side and not the other, because of the same relativistic Doppler-boosting effect that makes the accretion disk look asymmetrical.  The part of the jet aimed away from you will be vastly dimmed.

Here's a frame from a GRMHD simulation with ray-tracing (to show the lensing effect) of an accretion disk and jet close to the hole.  This is in the context of a low-accretion rate black hole, like Sagittarius A*, rather than a quasar.  Here the accretion disk is almost edge-on.

Image

No problem with the questions!  I may move these last couple posts to the Astronomy Q&A thread later. :)
 
A-L-E-X
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07 Apr 2017 08:37

Xoran wrote:
A-L-E-X wrote:
Source of the post Planets that orbit stars of different colors may even have plants of different colors- purple, pink or blue photosynthesis would be awesome to see too

Different-colored plants are already in SE :)


Plants are in SE?! I thought this was being saved for the next version?  Can they sway in the wind and do they create shadows (and multiple colored shadows for those that have planets around a multiple star system)?
 
A-L-E-X
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07 Apr 2017 08:38

Watsisname wrote:
spaceguy wrote:
Source of the post Why do quite a bit of accretion disks have giant bulges, often near the outside or inside?

I think you're referring to the gravitational lensing effect, which brings the far side of the accretion disk into view.  Let me annotate a screenshot of one with a few explanations and see if that answers your question.
Image

spaceguy wrote:
Source of the post Also could an accretion disk get hot enough for a corona to appear?

Absolutely!  Accretion disks are very hot -- hundreds of thousands to millions of degrees -- and will have a coronal wind of very hot plasma streaming off of them.
spaceguy wrote:
Source of the post Also also, how would an astrophysical jet appear with gravitational lensing near the black hole?

The lensing wont affect its appearance too much -- the more dramatic effect of the lensing is on the appearance of things which are behind the black hole.  The appearance of the jet depends more on the viewer's orientation.  If the jet is aimed somewhat towards you, then you mostly see that side and not the other, because of the same relativistic Doppler-boosting effect that makes the accretion disk look asymmetrical.  The part of the jet aimed away from you will be vastly dimmed.

Here's a frame from a GRMHD simulation with ray-tracing (to show the lensing effect) of an accretion disk and jet close to the hole.  This is in the context of a low-accretion rate black hole, like Sagittarius A*, rather than a quasar.  Here the accretion disk is almost edge-on.

Image

No problem with the questions!  I may move these last couple posts to the Astronomy Q&A thread later. :)

Wow that is a spectacular image- is that from SE?
 
A-L-E-X
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07 Apr 2017 08:42

DoctorOfSpace wrote:
spaceguy, here you go, same as the above instructions for installation

I had to reduce doppler shifting to fix an artifacting bug but otherwise this is close to what you requested.

► Show Spoiler


blackhole.glsl

Thanks, Doctor.  Is this something all of us should be downloading for more realistic black holes?
 
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Xoran
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07 Apr 2017 09:54

A-L-E-X wrote:
Source of the post Plants are in SE?! I thought this was being saved for the next version?  Can they sway in the wind and do they create shadows (and multiple colored shadows for those that have planets around a multiple star system)?

Nope plants aren't in SE, they are just textures :)
Space is too big to understand, so do not try to understand.
 
spaceguy
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07 Apr 2017 11:22

Watsisname wrote:
spaceguy wrote:
Source of the post Why do quite a bit of accretion disks have giant bulges, often near the outside or inside?

I think you're referring to the gravitational lensing effect, which brings the far side of the accretion disk into view.  Let me annotate a screenshot of one with a few explanations and see if that answers your question.
Image

spaceguy wrote:
Source of the post Also could an accretion disk get hot enough for a corona to appear?

Absolutely!  Accretion disks are very hot -- hundreds of thousands to millions of degrees -- and will have a coronal wind of very hot plasma streaming off of them.
spaceguy wrote:
Source of the post Also also, how would an astrophysical jet appear with gravitational lensing near the black hole?

The lensing wont affect its appearance too much -- the more dramatic effect of the lensing is on the appearance of things which are behind the black hole.  The appearance of the jet depends more on the viewer's orientation.  If the jet is aimed somewhat towards you, then you mostly see that side and not the other, because of the same relativistic Doppler-boosting effect that makes the accretion disk look asymmetrical.  The part of the jet aimed away from you will be vastly dimmed.

Here's a frame from a GRMHD simulation with ray-tracing (to show the lensing effect) of an accretion disk and jet close to the hole.  This is in the context of a low-accretion rate black hole, like Sagittarius A*, rather than a quasar.  Here the accretion disk is almost edge-on.

Image

No problem with the questions!  I may move these last couple posts to the Astronomy Q&A thread later. :)


By the bulge I meant the strange torus shape of matter around the accretion disk or inside it near the black hole.
 
A-L-E-X
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07 Apr 2017 11:28

Torii seem to reappear in cosmology and astronomy
 
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DoctorOfSpace
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07 Apr 2017 11:56

A-L-E-X, its not more realistic, not that I know of
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spaceguy
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07 Apr 2017 13:50

DoctorOfSpace wrote:
A-L-E-X, its not more realistic, not that I know of


Aren't there numerous photos of AGN with a tori structure?
 
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Watsisname
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07 Apr 2017 16:23

spaceguy wrote:
Source of the post By the bulge I meant the strange torus shape of matter around the accretion disk or inside it near the black hole.

I'm not sure what you mean.  Can you show a picture?  The accretion disk itself is just a thin flat disk.  Any apparent distortions to that shape are caused by gravitational lensing.
 
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DoctorOfSpace
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07 Apr 2017 17:09

spaceguy wrote:
Source of the post Aren't there numerous photos of AGN with a tori structure?

I think there may be one or two, don't know though.  In the future of SE 3D disks like that will be implemented but that is a bit further down the pipe.
CPU: Intel Core i7-5820K 4.2GHz 6-Core Processor - RAM: G.Skill Ripjaws V Series 32GB (4 x 8GB) DDR4-2400 Memory - GPU: EVGA GTX 1080 Ti FE 11GB
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spaceguy
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07 Apr 2017 17:52

Watsisname wrote:
spaceguy wrote:
Source of the post By the bulge I meant the strange torus shape of matter around the accretion disk or inside it near the black hole.

I'm not sure what you mean.  Can you show a picture?  The accretion disk itself is just a thin flat disk.  Any apparent distortions to that shape are caused by gravitational lensing.

http://www.faculty.virginia.edu/rwoclas ... -seeds.jpg
 
spaceguy
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07 Apr 2017 17:53

DoctorOfSpace wrote:
spaceguy wrote:
Source of the post Aren't there numerous photos of AGN with a tori structure?

I think there may be one or two, don't know though.  In the future of SE 3D disks like that will be implemented but that is a bit further down the pipe.

Do torus accretion disks flatten out after the compact object is done feeding or does it maintain that shape?
 
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Watsisname
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07 Apr 2017 18:18

Oh, I thought you were talking of something currently in Space Engine.

The dust torus is the best current model for the structure of AGN, which explains their physics and why they look different (quasar, blazar, Seyfert Galaxy, etc) from different viewing angles.  The accretion disk itself is fed from this dust torus.  To my knowledge there aren't any actual direct observations that show this, but I might be wrong.

Anyway as Doc said, right now SE is limited to thin flat accretion disks -- volumetric stuff may come later. :)

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