I M87 Black Hole Photos and the Spin Orientations

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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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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.

[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?

 

[aabottom]

Rob Jeffries offers a better explanation of Figure 5 in paper #5. [4]

[4] Why isn't the circumferential light around the M87 black hole's event horizon symmetric?

https://physics.stackexchange.com/q...t-around-the-m87-black-holes-event-horizon-sy

 

[anorlunda]

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.

 

[Bandersnatch]

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.

 

[davenn]

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

 

[lpetrich]

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.

 

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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.

 

[lpetrich]

It is not even a direct image. It is a reconstruction built using VLBI -- very long baseline interferometry.

 

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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.