Event Horizon Telescope, Milky Way supermassive black hole stream

In summary, the astronomers have revealed the first image of Sag A*, the black hole at the heart of our galaxy. Sag A* is tilted towards us, apparently due to gravitational forces exerted by the other stars in our galaxy. The researchers are still unsure of the spin axis of Sag A*, but they are confident that Newtonian models can provide an estimate.
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Sag A* (as seen by EHT):
1652362255068.jpeg
 
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My expectation was that the accretion disk would have been aligned with the galactic disk.
But it's tilted towards us - mugging for the camera.
There really is no reason it should be aligned to the galactic disk. The accretion disk would be a rather temporary and dynamic structure - with its axis of rotation determined on the entry path of its most recent captures.
 
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.Scott said:
The accretion disk would be a rather temporary and dynamic structure - with its axis of rotation determined on the entry path of its most recent captures.
Would the orbits of S2, S55 and s62 have an effect on the orientation of the accretion disk? I see that s55 has a closest approach to Sag A later this year.

https://iopscience.iop.org/journal/2041-8205/page/Focus_on_First_Sgr_A_Results
 
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.Scott said:
My expectation was that the accretion disk would have been aligned with the galactic disk.
But it's tilted towards us - mugging for the camera.
I don't know that we can make that assessment based on the image alone. After all, the curvature of space time around the BH is so immense that light from the top and bottom sides of the part of the disk that resides behind the BH (light that would normally be eclipsed by said celestial body, blocking our line of sight, were spacetime not so curved in that immediate region) gets bent up and over (and down and under) the event horizon, and directly along our line of sight as observers at a distance, giving it a face-on appearance anyways...

...so without more than just an image, I'm afraid its tough to say at just how much of an angle we're viewing the accretion disk (if we're viewing it at any angle at all). I hope that communicates, as when discussing such things, it can be difficult to convey concepts and ideas without illustrations, particularly animated ones.
 
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94JZA80 said:
I don't know that we can make that assessment based on the image alone. After all, the curvature of space time around the BH is so immense that light from the top and bottom sides of the part of the disk that resides behind the BH (light that would normally be eclipsed by said celestial body, blocking our line of sight, were spacetime not so curved in that immediate region) gets bent up and over (and down and under) the event horizon, and directly along our line of sight as observers at a distance, giving it a face-on appearance anyways...

...so without more than just an image, I'm afraid its tough to say at just how much of an angle we're viewing the accretion disk (if we're viewing it at any angle at all). I hope that communicates, as when discussing such things, it can be difficult to convey concepts and ideas without illustrations, particularly animated ones.
This isn't my assessment and its more than just the "image alone".

This is the assessment made by the team and reported Michael Johnson during the NSF presentation. His specific statement on this at 35:28 in the video. And the method for determining this is described from about 33:00 on - though I would suggest listening to the entire video.

And you're right, it's "tough to say [with authority]", but they did it.
 
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Oldman too said:
Would the orbits of S2, S55 and s62 have an effect on the orientation of the accretion disk? I see that s55 has a closest approach to Sag A later this year.

https://iopscience.iop.org/journal/2041-8205/page/Focus_on_First_Sgr_A_Results
Well, of course, "an effect" - but how much of an effect. Everything I've heard (including this video) suggests these kinds of estimations are based on a combination of computational models and hefty electric bills. This is true even when no black hole is involved.

Based on the video, they do not know the spin axis of Sag A*. So apparently the Sag A* accretion disk is not so affected by Sag A* tidal forces as to be readily evident. So I would guess that you could use a Newtonian model to come up with a pretty good estimate. The tidal forces of S2, S55, and S62 can impart some angular momentum to the Sag A* disk. Those forces would be proportional to the diameter of the disk but inversely proportional to the to the cube of the distances.

From various wiki pages: S2 (10 to 15 solar masses) gets about as close as 930au, S55 has a periapsis of 246au, and S62 (6.1 solar masses) has a periapsis of about 16au.
 
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Related to Event Horizon Telescope, Milky Way supermassive black hole stream

1. What is the Event Horizon Telescope?

The Event Horizon Telescope (EHT) is a global network of telescopes that work together to create an Earth-sized virtual telescope. It is designed to capture images of black holes and other objects with extreme precision.

2. What is the Milky Way supermassive black hole stream?

The Milky Way supermassive black hole stream refers to the region surrounding the supermassive black hole at the center of our galaxy. This stream is made up of gas and dust that is being pulled into the black hole's event horizon.

3. How does the Event Horizon Telescope capture images of the Milky Way supermassive black hole stream?

The EHT uses a technique called Very Long Baseline Interferometry (VLBI) to combine the signals from multiple telescopes around the world. This creates a virtual telescope with a diameter equal to the distance between the participating telescopes, allowing for high-resolution imaging of the black hole stream.

4. What have we learned from the images captured by the Event Horizon Telescope of the Milky Way supermassive black hole stream?

The EHT images have provided the first direct evidence of the existence of a supermassive black hole at the center of our galaxy. They have also allowed scientists to study the dynamics of the black hole and its surrounding environment, providing valuable insights into the nature of these mysterious objects.

5. How does the study of the Milky Way supermassive black hole stream contribute to our understanding of the universe?

Studying the supermassive black hole at the center of our galaxy can help us better understand the role of black holes in galaxy formation and evolution. It can also provide insights into the fundamental laws of physics, as these extreme objects test the limits of our current understanding of the universe.

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