M87 Black Hole Photos and the Spin Orientations

In summary, the conversation revolves around understanding the orientations and changes of angular momentum (spin) of the black hole and accretion disk in relation to the released M87 Black Hole images. The discussion includes references to videos and papers explaining the topic, as well as questions about the time scale and collinearity of the ejection jets and the use of VLBI in creating the images. It is clarified that the released images are not photos, but rather computer-generated reconstructions.
  • #1
aabottom
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M87 Black Hole Photos and the Orientations the Angular Momentum of the Black Hole and that of the Accretion Disk.

I’m trying to understand the orientations the angular momentum (let’s call it spin) of the black hole and that of the accretion disk. Veritasium has good video on the topic [1], but it does not relate to the released M87 images. The 5th paper of the EHT [2] (Figures 2, 3, and 5) has some good graphics, but the spins are displayed in 2 dimensions and, for me, are somewhat hard to comprehend. Maybe they are showing projections of the spin vectors.

I’d like to see some good 3-D graphics of the black hole spin and accretion disk spin next to the M87 Black Hole image.

Has anybody seen some good graphics on this topic?

[1] Veritasium, Published on Apr 9, 2019.

[2] The Event Horizon Telescope Collaboration et al. 2019 ApJL 875 L5. https://iopscience.iop.org/journal/2041-8205
 
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  • #2
I have some follow up questions.

A. Do the angular momentum (spin) vectors change with time? These photos of M87 seem to indicate different directions of the ejection jets. [3] If so, on what time scale- minutes, days, years? Maybe the photos are displayed in different orientations.

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[3] https://www.nationalgeographic.com.au/science/first-ever-picture-of-a-black-hole-unveiled.aspx

B. As I understand it, the ejection jets are nearly collinear with the black hole spin vector. Is this correct?

C. Is the angular momentum (spin) vector of the accretion disk is either parallel or anti-parallel with angular momentum (spin) vector of the black hole?
 
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  • #4
Also see this Vertasium video. He discusses the relationship between spin and the inner radius of the accretion disk and how that can be used to observe the spin rate.

 
  • #5
aabottom said:
A. Do the angular momentum (spin) vectors change with time? These photos of M87 seem to indicate different directions of the ejection jets. [3] If so, on what time scale- minutes, days, years? Maybe the photos are displayed in different orientations.
The photos are just rotated. Physical jet rotation at such a scale in such a short time would require matter to travel many times faster than the speed of light.
 
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  • #6
aabottom said:
M87 Black Hole Photos
Please understand ... the image that has been released is not a photo ... aka optical image
It's a computer generated image created from a large amount of data collected by radio telescopes
 
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  • #7
aabottom said:
I have some follow up questions.

A. Do the angular momentum (spin) vectors change with time? These photos of M87 seem to indicate different directions of the ejection jets. [3] If so, on what time scale- minutes, days, years? Maybe the photos are displayed in different orientations.

View attachment 241747
From the looks of it, it's different orientations. That M87 jet looks very similar between the two pictures, and given its length and the likely timeframe of observations of it, it likely has not changed much over that time.

But yes, a spinning black hole can precess, and I've found some mention of that in scholar.google.com.
 
  • #8
davenn said:
Please understand ... the image that has been released is not a photo ... aka optical image
It's a computer generated image created from a large amount of data collected by radio telescopes
Yes, thank you. I know this. The term Photo is just poetic license for the photons at 1.33 mm wavelength (that is 230.6 GHz) of the radio telescope. The image is a radio-graphic image, one might say.

To avoid confusing people, I should stop using the term photo when referring to the M87 black hole "image". But I'm not sure the term "image" would any less confuse the layman.
 
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  • #9
It is not even a direct image. It is a reconstruction built using VLBI -- very long baseline interferometry.
 
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  • #10
lpetrich said:
It is not even a direct image. It is a reconstruction built using VLBI -- very long baseline interferometry.
Yes, I have done research in optical/ infrared sparse aperture imaging systems. When the pupil plane data is transformed to the focal plane, the results can be considered a reconstructed image.
 

1. What is the significance of the M87 black hole photos?

The M87 black hole photos are significant because they provide the first direct visual evidence of a black hole. They also confirm Einstein's theory of general relativity and give insight into the behavior of black holes.

2. How were the M87 black hole photos taken?

The M87 black hole photos were taken using a network of eight telescopes around the world called the Event Horizon Telescope (EHT). The EHT uses a technique called very-long-baseline interferometry (VLBI) to combine the data from each telescope and create an image with a resolution equivalent to a single telescope the size of the Earth.

3. What is the spin orientation of the M87 black hole?

The M87 black hole has a clockwise spin orientation, meaning it rotates in the same direction as the accretion disk of gas and dust surrounding it. This was determined by analyzing the polarization of the light emitted from the black hole's accretion disk.

4. How does the spin orientation of the M87 black hole affect its behavior?

The spin orientation of a black hole can affect its behavior in several ways. For example, it can determine the direction of the black hole's jets, which are powerful streams of particles that are emitted from the poles. It can also affect the strength of the black hole's gravitational pull and the shape of its accretion disk.

5. What new insights have we gained from the M87 black hole photos and spin orientation?

The M87 black hole photos and spin orientation have provided new insights into the behavior of black holes, such as confirming the existence of an event horizon and the validity of general relativity. They have also given scientists a better understanding of how black holes evolve and interact with their surroundings.

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