r = 1.0001 M; Click on the
images to enlarge
What happens below r = 1.0001 M?
At the moment of writing, my code experiences a series of problems for
r < 1.0001
M in addition to becoming extremely
slow. I presume that the number of
ghost images of significant angular size will be ever increasing as the
orbit gets closer and closer to the black hole, however, I have not yet
been able to check this.
Videos
For the 7 first values of
r
shown above, the images above are actually the first frame of 1800
frame long videos
which all show a complete orbit around the black hole. Therefore, each
video runs in 1 minute or 1'12", depending whether your player runs at
30 or 25
frames per second. Of course, the actual orbital period has to be
scaled with the
corresponding value of
M one
uses. An important thing to note is that when close to the black hole,
the angular distance between the primary image of the Milky Way and its
first ghost images is rather small (less than 10 degrees, say, for
r = 1.02
M, and far less for smaller
r). This means that when the
observer makes one turn around the black hole, then the whole celestial
sphere is moving on the right by only 10 degrees, each image of it
replacing the next one! In other words, for a fixed
orbital period, the angular displacement of the celestial sphere is
much larger for large orbital radius than for a small one. Whether or
not this is compensated by the fact that the orbital period at fixed
M decreases with
r is not known to me at the time of
writing,
however, it might happen
that, contrarily to naive expectation, the view seen by an orbiting
observer becomes almost still as r approaches the horizon!