Picture of black hole...

[Guest]

A

30 minutes ago, Tykeviewer said:

It has been described as “perfectly circular”, but to me it looks elliptical, or possibly even ‘egg-shaped’.  Has anyone seen any discussion on that aspect?

If the gas is spinning around the black hole then think of how a circle looks if it is tilted at an angle to the viewer; an ellipse.

[andrew s]

2 minutes ago, Tykeviewer said:

If it is elliptical because of its spin, then it would imply it has volume. A singularity, however, cannot have volume. ?

But the event horizon can and does.

Regards Andrew 

[Tykeviewer]

The second promoted comment on this article suggests that it should appear the same, regardless of the point of view of the observer. I don’t really follow the explanation though.

https://arstechnica.com/science/2019/04/event-horizon-telescope-gives-us-first-images-of-what-its-named-for/

[Tykeviewer]

Wouldn’t the shape of the event horizon be determined by the shape of the mass acting on it - in other words the shape of the black hole (which cannot have shape if it is a singularity - so back to square 1 ? ).

[andrew s]

18 minutes ago, Tykeviewer said:

Wouldn’t the shape of the event horizon be determined by the shape of the mass acting on it - in other words the shape of the black hole (which cannot have shape if it is a singularity - so back to square 1 ? ).

A black hole is defined by mass, charge and spin. You need to study the subject to understand it impact on the event horizon.

Regards Andrew 

[Tykeviewer]

I tried, but didn’t understand a word of it ?

https://physics.stackexchange.com/questions/72824/what-is-the-shape-of-a-black-hole

[Stu]

8 hours ago, andrew s said:

Thanks a major step forward in seeing the acretion disc of a black hole.

Regards Andrew 

Are we not seeing what is effectively the event horizon Andrew?

[andrew s]

5 minutes ago, Stu said:

Are we not seeing what is effectively the event horizon Andrew?

In effect yes. I am not exactly sure if the black edge is the projected event horizon as the light is bent and distorted round it. I would have to look at the paper they have published to be sure.

Regards Andrew 

[saac]

1 hour ago, Stu said:

Are we not seeing what is effectively the event horizon Andrew?

The  veritasium video has a good explanation of what we are seeing in the image - if I understood it correctly we are not looking at the event horizon directly rather than a projection of the event horizon (the shadow) made apparent through gravitational lensing of the accretion disc which includes near and far side warped together by the massive gravity field. The resulting shadow is several times (almost x 3) the value of the Schwarzchild radius due to the distortion.

Jim 

 

 

 

Edited April 10, 2019 by saac

[saac]

2 hours ago, Tykeviewer said:

Wouldn’t the shape of the event horizon be determined by the shape of the mass acting on it - in other words the shape of the black hole (which cannot have shape if it is a singularity - so back to square 1 ? ).

As you say the singularity does not have a shape by definition; the geometry of the event horizon follows  from the gravitational field associated with the singularity.  What the image provides, amongst other things, is yet more support to the validity of Einstein's General Relativity which effectively predicted such heavy distortion of space-time.

Jim

[Highburymark]

6 hours ago, ollypenrice said:

Taking the black hole from its first theoretical conception (John Michel,1783) to it's first direct image today, has to be a great moment in science. Suppose they had been unable to find it...

Spiral galaxies began like this with Lord Rosse in 1848...

... whereas today an amateur relying entirely on the expertise of the technical experts behind his equipment can produce this (or better than this) from a small telescope in his back yard.

I think that today we are witnessing one of the greatest astrophotos of all time.

Olly

 

 

 

 

 

 

Couldn't agree more Olly

[Sunshine]

An incredible effort involving around 200 researchers, an object with almost mythical status, the subject of countless movies, books, and stories. Finally, today,  it’s signature has been captured for the first time ever, if the image consisted of 10 pixels it would still be monumental. The difficulty of capturing this accretion disc is being overlooked.

 

[niallk]

4 hours ago, Knight of Clear Skies said:

Very good summary, well worth watching. Thanks Ruud. Surprised to see the Sgr A* image there too.

Great vid - and an unbelievable technical achievement!

Yes - I didn't think the Sgr A* image was released???

Here's an interesting size comparison- apologies if someone has already posted this and I missed it:

Edited April 11, 2019 by niallk

[MarsG76]

That is so awesome... I wonder if there will be (or when will be) the first amateur astrophotographer to image a black hole?

[beka]

Science at its best. Congratulations to the guys who did this!

Edited April 11, 2019 by beka

[Knight of Clear Skies]

1 hour ago, MarsG76 said:

I wonder if there will be (or when will be) the first amateur astrophotographer to image a black hole?

Arguably, we already have. The effects of accretion disks are visible, there are plenty of Quasars within reach of amateur equipment (up to 12 billion light years away) and the M87 jet is resolvable. The EHT also relies on the accretion disk for its image but has the resolution to show the shadow of the accretion disk.

[wxsatuser]

BBC shows a photo of some one with 8 sets of hard drives from the 8 scopes in the project.

Can someone tell me how the SPT got data from M87 when M87 is at Dec +12.

 

[Stu]

38 minutes ago, wxsatuser said:

BBC shows a photo of some one with 8 sets of hard drives from the 8 scopes in the project.

Can someone tell me how the SPT got data from M87 when M87 is at Dec +12.

 

Good point, well presented ?

I'm not sure!!!

[Knight of Clear Skies]

4 hours ago, wxsatuser said:

Can someone tell me how the SPT got data from M87 when M87 is at Dec +12.

I believe the SPT was only used to gather data on Sgr A*.

Edited April 11, 2019 by Knight of Clear Skies

[Ben the Ignorant]

How come they didn't try with Andromeda's black hole? It's big and not too distant.

[Knight of Clear Skies]

2 minutes ago, Ben the Ignorant said:

How come they didn't try with Andromeda's black hole? It's big and not too distant.

It's much smaller and less active than M87, despite being far closer the angular size is a lot less. (The apparent size of Sgr A* is only a little more than M87 despite being in our own galaxy.)

[ollypenrice]

12 hours ago, Knight of Clear Skies said:

It exceeds my expectations, I find the image both interesting and inspiring. It's encouraged me to learn about the subject and think about the implications of living with such a monster in your galaxy. M87 spits out a jet 5,000 light years long with the energy - If my math is correct - of 200 million, trillion Deaths Stars. Continually. What effect does that have on star formation, or any planets that stray across its path?

 

 

observations of neutral hydrogen were an essential tool to mapping out the structure of our own galaxy.

In Jodrell Bank's one year Introduction to Radio Astronomy Course we were able to conduct this experiment using a small radio telescope which looked for different peaks in the 21cm line within the Galactic plane, each peak corresponding with a spiral arm of the Milky Way. The task was then to identify the spiral arms. It was a wonderful thing to do.

Olly

[ollypenrice]

saac's video link above is an absolute 'must' with regard to understanding the image. It's more complicated than I realized and the image confirms theory in more ways than I'd appreciated as well. The new picture just got even better for me. Thanks for the link, saac.

Olly

Edited April 11, 2019 by ollypenrice

[Mick J]

Newspapers love it, snapshot from the Metro, apologies.

 

 

[Stu]

57 minutes ago, ollypenrice said:

saac's video link above is an absolute 'must' with regard to understanding the image. It's more complicated than I realized and the image confirms theory in more ways than I'd appreciated as well. The new picture just got even better for me. Thanks for the link, saac.

Olly

Yes, agreed. It really helped me to understand what is going on.

One confusion I have though is about the definition of the Event Horizon. It seems that even light passing further away than the Event Horizon gets pulled in. Am I correct in thinking that the Event horizon is the point at which light travelling radically away from the centre cannot escape, so the actual sphere where light can be captured and pulled in is much bigger for light just passing by?