APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Comments and questions about the APOD on the main view screen.
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APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by APOD Robot » Sun May 01, 2022 4:05 am

Image First Horizon-Scale Image of a Black Hole

Explanation: What does a black hole look like? To find out, radio telescopes from around the Earth coordinated observations of black holes with the largest known event horizons on the sky. Alone, black holes are just black, but these monster attractors are known to be surrounded by glowing gas. This first image resolves the area around the black hole at the center of galaxy M87 on a scale below that expected for its event horizon. Pictured, the dark central region is not the event horizon, but rather the black hole's shadow -- the central region of emitting gas darkened by the central black hole's gravity. The size and shape of the shadow is determined by bright gas near the event horizon, by strong gravitational lensing deflections, and by the black hole's spin. In resolving this black hole's shadow, the Event Horizon Telescope (EHT) bolstered evidence that Einstein's gravity works even in extreme regions, and gave clear evidence that M87 has a central spinning black hole of about 6 billion solar masses. Since releasing this featured image in 2019, the EHT has expanded to include more telescopes, observe more black holes, track polarized light,and is working to observe the immediately vicinity of the black hole in the center of our Milky Way Galaxy.

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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by Ann » Sun May 01, 2022 5:17 am

Is an image of the central supermassive black hole of the Milky Way, Sgr A*, coming up? The people behind the portrait of the supermassive black hole in M87 have said that they will take a picture of Sgr A*, too. Perhaps it is coming soon?

Go to this "Youtube short" by Dr Becky to hear her say a few words about it.

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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by alter-ego » Sun May 01, 2022 5:39 am

APOD Robot wrote: Sun May 01, 2022 4:05 am ...
Pictured, the dark central region is not the event horizon, but rather the black hole's shadow -- the central region of emitting gas darkened by the central black hole's gravity. The size and shape of the shadow is determined by bright gas near the event horizon, by strong gravitational lensing deflections, and by the black hole's spin.
...
Considering a Schwarzschild BH (non-rotating), the shadow diameter is 2.6 times the event horizon diameter for a BH very far away (e.g Milky Way BH)
Shadow of black holes at local and cosmological distances
 
BH Shadow misconeptions - Bottom view is correctJPG.jpg
 
Face-on view.jpg
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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by alter-ego » Sun May 01, 2022 5:50 am

Ann wrote: Sun May 01, 2022 5:17 am Is an image of the central supermassive black hole of the Milky Way, Sgr A*, coming up? The people behind the portrait of the supermassive black hole in M87 have said that they will take a picture of Sgr A*, too. Perhaps it is coming soon?

Go to this "Youtube short" by Dr Becky to hear her say a few words about it.

Ann
Yes, I've read it's still in development stages, but I didn't see a planned date. There are more telescopes joining in, I presume for more data to help with resolution and fidelity. Back when M87 was imaged, they knew that the MW BH is harder to image. I can't remember the details, but I believe the task is harder because it's smaller and maybe not as well positioned wrt its accretion disk(?).

It looks like the EHT group will be presenting "groundbreaking" results this May 12
https://www.space.com/event-horizon-tel ... ay-results
Last edited by alter-ego on Sun May 01, 2022 5:59 am, edited 1 time in total.
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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by AVAO » Sun May 01, 2022 5:59 am

Last edited by AVAO on Sun May 01, 2022 10:03 am, edited 1 time in total.

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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by heehaw » Sun May 01, 2022 9:00 am

Karl Schwarzschild predicted what you see in the photo, a black hole of mass m, while fighting for Germany on the Eastern Front in World War I: http://henry.pha.jhu.edu/bigfour.png

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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by De58te » Sun May 01, 2022 1:09 pm

Maybe it is a defect of my computer monitor but to me the central black shadow still looks a little brighter to me than the surrounding black at the edges of the photo. It even looks almost a shade of brown compared to the black at the edges. Although it is impossible for the star light behind the shadow to show through the black hole, maybe that brown is haze light from the stars in the galaxy in front reflecting off some dust particles that are in direct line of the black hole? But then what is producing the black shadow at the sides? Surely there must be some stars from the back portion of the galaxy visible there.

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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by Eclectic Man » Sun May 01, 2022 1:42 pm

If you have any questions about black holes, you can ask LIGO at:

https://www.ligo.caltech.edu/page/ask-ligo

I have in the past and received a prompt, comprehensive and very informative reply.

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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by Chris Peterson » Sun May 01, 2022 2:16 pm

De58te wrote: Sun May 01, 2022 1:09 pm Maybe it is a defect of my computer monitor but to me the central black shadow still looks a little brighter to me than the surrounding black at the edges of the photo. It even looks almost a shade of brown compared to the black at the edges. Although it is impossible for the star light behind the shadow to show through the black hole, maybe that brown is haze light from the stars in the galaxy in front reflecting off some dust particles that are in direct line of the black hole? But then what is producing the black shadow at the sides? Surely there must be some stars from the back portion of the galaxy visible there.
Note that the spatial resolution of the image is about the same size as the central shadow. In simple terms, that means that we're looking at a very blurry image, so a lot of energy in the imaged central region (as opposed to the actual center region) is coming from the (imaged) ring around it. The white ring in the image below shows the resolution of the data.
_
res.png
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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by orin stepanek » Sun May 01, 2022 3:45 pm

M87bh_EHT_2629.jpg
I'm stqyina away from this beast!
(2).jpg
But love cake donuts
.jpg
Scholarly kitty! 8-)
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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by E Fish » Mon May 02, 2022 3:05 am

es, I've read it's still in development stages, but I didn't see a planned date. There are more telescopes joining in, I presume for more data to help with resolution and fidelity. Back when M87 was imaged, they knew that the MW BH is harder to image. I can't remember the details, but I believe the task is harder because it's smaller and maybe not as well positioned wrt its accretion disk(?).
I seem to recall (unfortunately, not remembering the source) reading that the issue was a combination of a lot more dust in the way and the black hole itself being less active than the one in M87. That was in addition to the fact that it's smaller than M87's.

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Re: APOD: First Horizon-Scale Image of a Black... (2022 May 01)

Post by Ann » Mon May 02, 2022 4:01 am

E Fish wrote: Mon May 02, 2022 3:05 am
es, I've read it's still in development stages, but I didn't see a planned date. There are more telescopes joining in, I presume for more data to help with resolution and fidelity. Back when M87 was imaged, they knew that the MW BH is harder to image. I can't remember the details, but I believe the task is harder because it's smaller and maybe not as well positioned wrt its accretion disk(?).
I seem to recall (unfortunately, not remembering the source) reading that the issue was a combination of a lot more dust in the way and the black hole itself being less active than the one in M87. That was in addition to the fact that it's smaller than M87's.

Let's hope so! :shock: 😱

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