The images below represent an accretion disk around a black hole as it would appear to a distant observer. A relativistic ray-tracer calculated the photon trajectories; the images may appear distorted as a result of the gravitational lensing in the strongly curved spacetime. Color indicates the frequency shift of observed photons across the face of the disk, assuming that the sources are in orbit around the black hole.
These postage-stamp images are links to gzipped-postscript. The postscript is not stand-alone--it will need to be resized as needed. (Caution: these files are between 0.5 and 2 Mbyte, even when compressed.)
This image is a
geometrically thin disk around an extreme Kerr (maximally rotating)
black hole, seen at an inclination of 75 degrees. The inner radius of
this "Keplerian" (circularly rotating) disk is at 1.24 R_g, where R_g
= G * M/c^2 is the gravitational radius of a black hole with mass
M. The outer radius is at 6 R_g. The colors correlate with the
observed frequency of light from the disk; the white strip divides
redshifted and blueshifted regions. Note that the asymmetric
appearance of the inner disk edge is the result of the frame-dragging
effect (gravitomagnetism) of black hole rotation.
This disk is
located around a Schwarzschild (non-rotating) black hole. It extends
from near the horizon at 2 R_g to about 12 R_g, and is seen at an
inclination angle of 30 degrees. At large radii the disk material is
on circular orbits, but at a radius of 6 R_g, these orbits become
unstable. Thus at 6 R_g, the disk material begins a "free fall" orbit
which spirals toward the hole. The color map here (and in the images
below) indicates only relative changes in observed frequency--most of
the photons are actually redshifted.
A model
turbulent Schwarzschild disk is shown here. Turbulence is required to
help disk material lose angular momentum so it can accrete onto the
hole. In doing so it may generate the powerful radiation which we
observe in quasars and active galaxies. This disk also has finite
thickness associated with the size of turbulent cells (patches of
similar color) in the outer disk. The freefalling material nside 6 R_g
is smooth in texture; there, no turbulence is required for accretion
onto the hole.
A geometrically thin,
non-turbulent disk around an extreme Kerr black hole. Disk parameters
are similar to the preceding two images, except with the inner radius at
1.24 R_g.
Same as above,
except with turbulence. Note that the disk is turbulent all the way
down to the inner edge, and that the overall flow is approximately
circular.
Finally, this
image is of a disk around an extreme Kerr black hole with inner and
outer radii of 1.24 R_g and 6 R_g respectively. The intensity of the
photons is calculated assuming that the disk is emitting in an
optically thick line; Using G. Rybicki's adaptation of photon-escape
probability formalism, we can understand the dark stripes as
directions where photons from inside the disk are scattered out of the
line of sight by surface material. In the bright regions, velocity
shear shifts the frequency of the surface material enough so that
it cannot reduce the flux by line scattering.