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First Image of Black Hole

Gravitas Hunt

Gravitas Hunt

On one, not scared
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Looks like we have the first image of a black hole, courtesy of the Event Horizon Telescope!

Article:
Astronomers Capture First Image of a Black Hole
An international collaboration presents paradigm-shifting observations of the gargantuan black hole at the heart of distant galaxy Messier 87



The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. Today, in coordinated press conferences across the globe, EHT researchers reveal that they have succeeded, unveiling the first direct visual evidence of a supermassive black hole and its shadow.
This breakthrough was announced today in a series of six papers published in a special issue of The Astrophysical Journal Letters. The image reveals the black hole at the center of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster. This black hole resides 55 million light-years from Earth and has a mass 6.5 billion times that of the Sun.


Edit: looks like there are links to the papers here.
First one
 
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And what a beauty it is!

Now, it's possible that I'm misinterpreting the image, but here's what I think is going on. Black holes are interesting; that black circle in the centre is indeed the event horizon, but in fact it's the entire event horizon, including the side that is facing away from us. They bend light quite severely, after all...

It's brighter at the bottom, bottom-right side; that should be doppler shift from the accretion disk moving towards us. It's similar to everyday doppler shift, but of course in this case the velocity difference is very nearly the speed of light, so it's quite a noticeable brightening.

In other words, we are not looking at the black hole from the pole, nope. We're looking at it edge-on; the lower-right bright spot is where it's rotating towards us. If you look carefully, you can see the accretion disk itself as a dim, diagonal stripe across the image...

So what's with the much brighter ring around the hole?

Well, that's still the accretion disk. It looks like that from any angle; the light it emits behind the hole, from our perspective, gets bent to appear as if it's a circle surrounding the hole -- regardless of the actual angle. This is better explained visually, so here's a video describing the phenomenon:



(A summary of the video? Look above.)

===

On a curious note, at the same time as we received our first pictures of the black hole, a different group of scientists announced the discovery of a new hopefully-extinct deep-sea species. Behold, Sollasina Cthulhu:

 
I'm eagerly waiting for the data for Sag A* to come out because I want to do a virgin/chad meme with the two of them.
 
Hmm an actual picture of a Black Hole and the political black hole that is Brexit at the same time.

What a time to be alive.
 
Baughn said:
It's brighter at the bottom, bottom-right side; that should be doppler shift from the accretion disk moving towards us. It's similar to everyday doppler shift, but of course in this case the velocity difference is very nearly the speed of light, so it's quite a noticeable brightening.
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I'm a bit confused by this, since I thought doppler shifts affected frequency, not brightness. Is this chart showing something like total energy emission?
 
Article:
Astronomers announced on Wednesday that at last they had captured an image of the unobservable: a black hole, a cosmic abyss so deep and dense that not even light can escape it.

For years, and for all the mounting scientific evidence, black holes have remained marooned in the imaginations of artists and the algorithms of splashy computer models of the kind used in Christopher Nolan's outer-space epic "Interstellar." Now they are more real than ever.

"We have seen what we thought was unseeable," said Shep Doeleman, an astronomer at the Harvard-Smithsonian Center for Astrophysics, and director of the effort to capture the image, during a Wednesday news conference in Washington, D.C.

The image, of a lopsided ring of light surrounding a dark circle deep in the heart of the galaxy known as Messier 87, some 55 million light-years away from Earth, resembled the Eye of Sauron, a reminder yet again of the implacable power of nature. It is a smoke ring framing a one-way portal to eternity.


well the Event Horizon Telescope managed to captured an image of a black hole, which is a pretty awesome thing for science to have been able to do. And this leads me to wonder what else we thought we would not be able to do that we eventually will be able to do.
 
Skelm said:
I'm a bit confused by this, since I thought doppler shifts affected frequency, not brightness. Is this chart showing something like total energy emission?
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Probably, I guess? I haven't found a technical paper yet.

The photons are blueshifted, so the overall energy output is higher. The photon count should be about the same.
 
Skelm said:
I'm a bit confused by this, since I thought doppler shifts affected frequency, not brightness. Is this chart showing something like total energy emission?
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Baughn said:
Probably, I guess? I haven't found a technical paper yet.
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It's due to the relativistic Doppler effect, which has some extra features. Specifically in this case, it's Relativistic Beaming.

Technical papers are linked in the OP. Part V has this:
Article:
The ring is brighter in the south than the north. This can be explained by a combination of motion in the source and Doppler beaming. As a simple example we consider a luminous, optically thin ring rotating with speed v and an angular momentum vector inclined at a viewing angle i > 0° to the line of sight. Then the approaching side of the ring is Doppler boosted, and the receding side is Doppler dimmed, producing a surface brightness contrast of order unity if v is relativistic.
 
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gustavo said:
Wow.. we are like an inconspicuous, insignificant, irrelevant nano-organism in this playground of giants.
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Normally I'd protest, but that's... that's fair, actually.

XKCD makes a good point. Black holes are the densest objects in the universe, the densest objects that can possibly exist, and we're looking at a black hole larger than our solar system.
 
Not to sound like a rube, but that doesn't exactly look much different from all the other images I've seen in like movies and stuff. I guess a good job with the models guys.
 
Khona Moshr said:
You see I went searching to see if such a thread existed and forgot we had a science and technology subforum since I dont post there



I wonder how much more mass does it have over the Solar system
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6.5B solar masses. Interestingly that makes the sphere under the event horizon less dense than the sun itself.

Obviously, that doesn't make any sense since the mass should be in a singularity at the centre of that sphere; this is just to draw attention on the fact that the sphere covered by the event horizon isn't the singularity.
 
yes, prior to this photo, the movies guys did the black hole images and got it right. Even more awesome, Einstein "figured out and visualized" this black hole thingy in his mind and got it right. Unbelievable..

VolantRedX said:
Not to sound like a rube, but that doesn't exactly look much different from all the other images I've seen in like movies and stuff. I guess a good job with the models guys.
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Baughn said:
Normally I'd protest, but that's... that's fair, actually.

XKCD makes a good point. Black holes are the densest objects in the universe, the densest objects that can possibly exist, and we're looking at a black hole larger than our solar system.
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Actually, with supermassive black holes like this one, they actually aren't all that dense at all. This thing only has a density of ~0.45 kg/m3​, which is probably less dense than the air you're breathing right now.

Schwarzschild radius of ~1.9*1013​ m for a mass of 6.5*109​ Solar masses or ~1.3*1040​ kg. A sphere of that radius has a volume of ~2.9*1040​ m3​. This black hole is apparently spinning so it isn't quite spherical but eh, close enough.
 
It's counter-intuitive, but any fixed positive density of matter, over a sufficiently large volume, will form an event horizon. The Schwarzschild radius increases linearly with mass, while volume increases with the third power.
 
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