The first direct image of a black hole was provided by the event horizon telescope. The image was powerful but not detailed. A blurry orange donut is what it appears to be.
The real meat of the discovery was in the data. A recent study shows that there is a lot more in the data than we have seen.
The glow of the black hole is not shown in the EHT image. Light is not emitted by black holes directly.
The glow is not due to jets of plasma or a torus of superheated gas around the black hole.
The light was focused by the black hole.
Gas and radio light illuminate the black hole. The warping of spacetime causes a beam of light to change direction.
The light from the stars and other objects can change direction if it's close to a black hole.
It could either make a right-angle turn or head back to where it came. The closer you are to the black hole, the more radical the change is.
We can only see the light that is focused on us when we look at it from the other direction. We should be able to see a beam of light looping around the black hole.
The black hole can be used as a lens. Light can travel very close to the black hole. The thin photon ring is what we should see.
The rotation of the black hole will make part of the light brighter. The ring size is dependent on the mass of the black hole and the brightness of the brighter region.
The photon ring is not shown in the image. There is space between us and the black hole.
The light has to travel through the cold gas to reach us. The light scatters and makes the image blurry. The new study is coming here.
The diffuse glow of the EHT image shows both the black hole and the diffuse gas surrounding it. There are two images in the data.
The blurry glow of the surrounding region is the other one. The team was able to see the black hole's photon ring using new techniques.
It's an example of how data can be analyzed in a new way. There is a lot of data that is gathered by modern astronomy. We can see layers hidden under the surface as we learn how to process data better.
This article was published in the past. The original article is worth a read.