****Notes on "Views of Black Holes"**** www.astro.umd.edu/~rauch/ViewsBHs/ Kevin P. Rauch, JHU & UMD rauch@astro.umd.edu The video consists of six independent segments ("episodes") and has a total running time of 5 minutes (24 fps) and a resolution of 240x200. The entire movie as one MPEG file (ViewsBHs.mpg) is also available. Optimum playback requires 16-bit color and a CPU equivalent to a 200 MHz Pentium or faster. Individual segments average 3MB file size (17MB for the combined movie). The movie depicts a thin, alpha-type accretion disk with a nu^-1 spectrum observed at a frequency nu_obs = 0.5 k T6 / h, where T6 is the (arbitrary) temperature at a radius r = 6 M in the disk (which sets the zero-point for the power law T(r) scaling). To the plain disk four circular (rigidly rotating) hot spots were added, arranged symmetrically about the disk at r = 8 M; they are not all the same size, allowing visual tracking of rotational phase. The color map is physically coded---red is coolest (lowest I_nuobs), blue/white is hottest (highest I_nuobs). The color map is fixed between episodes---i.e., the same color represents the same I_nuobs throughout. Roughly 30,000,000,000(!) null geodesics were traced to make the high-resolution movie (640x480x30Hz, available on VHS tape or CD-ROM only). These animations may be freely redistributed and used, for non-profit purposes, subject to proper acknowledgement of the author. Episode I: "The Phantom Monster" --------- A stationary observer is located on the spin axis of the hole at r = 10 M. The hole is spun up from a = 0 (Schwarzschild) to a = 0.998 and back to a = 0, and the disk is assumed to respond instantaneously. For this observer the location of the lensed rings is nearly independent of a, whereas the inner disk edge rapidly approaches the horizon as a -> 1. Episode II: "Into the Fray" ---------- The viewpoint shifts from the axis (inclination i = 90 deg) to near the disk plane of the a = 0 hole. Once in the plane, the hole is again spun up to a = 0.998 and spun down back to Schwarzschild; Doppler shifts and distortions vary accordingly. Episode III: "Plumbing the Depths" ----------- The viewpoint slowly descends from r = 10 towards the horizon for an a = 0 hole, as if viewing the camera feed of a tethered probe that is being slowly lowered into the hole. At the photon orbit the probe momentarily stops and pans around to face local zenith (infinity) instead of the hole; just outside the horizon the probe is stopped and reeled in to take a last look back at the lensed disk images. Episode IV: "A One-way Ticket" ---------- A probe is dropped from a large distance and free-falls into an a = 0.998 hole. The segment begins when the probe reaches r = 6 and displays the fall as recorded by the probe (i.e., constant proper time interval between frames). The view window here is a cut-open cylindrical projection (the left and right edges join and correspond to the view directly *behind* the observer). Episode V: "Pacman Strikes Back" --------- The same as IV, only showing the telemetry as received by the distant station, i.e., constant coordinate time interval between frames; as expected, the probe appears to "freeze" at the horizon (r = 1.0632). Watch for the ending Easter egg surprise! :-) Episode VI: "Return to the Dark Side" ---------- Similar to IV and V, but now the probe slowly spirals into the hole, as if caught in the accretion flow itself. The video is best considered as time-lapse photography taken in equal proper time increments that far exceed the rotational period, which causes the beating effect seen in the hot spots. When the probe passes the inner disk edge at r = 1.237, the multiple lensed images become visible and the universe suddenly looks very confusing! Note that for most of the time, the observer is inside the retrograde photon orbit but outside the prograde photon orbit.