# Black hole collapse - ray tracing

• tom.stoer
In summary: Assuming I'm right in thinking that ray tracing is just null geodesics, the static schwarzschild should be the same as oppenheimer-snyder if you make sure light only passes in the external part of the metric, as the metric is the same.Yes--in a realistic simulation of what might be seen through a telescope.
tom.stoer
I know several raytraycing results for static Schwarzschild black holes, but I have never seen something similar for collapse models like Oppenheimer-Snyder or Vaidya.

Are there reliable raytraycing results showing the effect on light rays from far distant light emitters observed by (far distant) observers?

no ideas?

push

What do you mean by raytracing results? Mathematical theorems? Simulated images? Characterizations of possible orbits? The Vaidya metric represents the collapse of a field of incoherent radiation, so I would think that the geodesics would be the same as the trajectories of the infalling matter, which would also be the same as the rays in an optical simulation.

Is this of any interest? Seahra, "An introduction to black holes," http://www.math.unb.ca/~seahra/resources/notes/black_holes.pdf Has a bunch of discussion of horizons in the Vaidya metric.

Assuming I'm right in thinking that ray tracing is just null geodesics, the static schwarzschild should be the same as oppenheimer-snyder if you make sure light only passes in the external part of the metric, as the metric is the same.

I'm guessing this may not be particularly helpful, though.

Last edited:
pervect said:
Assuming I'm right in thinking that ray tracing is just null geodesics, the static schwarzschild should be the same as oppenheimer-snyder if you make sure light only passes in the external part of the metric, as the metric is the same.
Yes.

The Schwarzschild portion is growing with t to smaller r(t), therefore the images of rays not crossing r(t) are rays like in Schwarzschild spacetime with smaller r(t) but constant mass M.

But what I am especially interested in is the image of rays
a) passing through the dust ball (assuming that the dust is transparent)
b) close to r(t) in the far future where r(t) → 2M asymptotically

So realistic simulations of what might be seen through a telescope? I think the studies so far have been studies of the feasibility of resolving the event horizon of Sag A* using infrared. I would be surprised if anyone had tried simulating anything else, because Sag A* is the only realistic prospect for us to resolve.

## 1. What is "black hole collapse - ray tracing"?

"Black hole collapse - ray tracing" is a theoretical concept in astrophysics that involves using mathematical calculations and computer simulations to study the gravitational collapse of a black hole and the behavior of light rays in its vicinity.

## 2. How is ray tracing used to study black hole collapse?

Ray tracing involves tracing the paths of light rays as they pass through the warped space and time around a collapsing black hole. By analyzing the paths of these rays, scientists can gain insight into the behavior of matter and energy near the event horizon of a black hole.

## 3. Why is studying black hole collapse important?

Studying black hole collapse is important because it can help us understand some of the most extreme and mysterious phenomena in the universe. It can also provide valuable insights into the nature of gravity and the fundamental laws of physics.

## 4. What are some potential applications of studying black hole collapse?

Studying black hole collapse can have practical applications in fields such as astrophysics, cosmology, and space travel. It can also help us better understand and predict the behavior of black holes, which are crucial objects in the formation and evolution of galaxies.

## 5. Are there any limitations to using ray tracing to study black holes?

While ray tracing is a powerful tool for studying black hole collapse, it has its limitations. For example, it cannot fully account for quantum effects near the event horizon, and it relies on simplifying assumptions that may not accurately reflect the complexities of the real universe.

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