Spherical Accretion of Theoretical Astrophysicists

At the Cambridge AGN meeting in 1979, Dick McCray presented his now-famous cartoon depicting the spherical accretion of theoretical astrophysicists onto a fashionable new idea. He described how they are first attracted to the idea when they innocently venture inside the accretion radius. Many fly through on their hyperbolic orbits without getting trapped. Occasionally, however, two astrophysicists collide, generating a great deal of heat (but not always much light). These hapless souls can no longer leave the sphere of influence of the fashionable new idea, but are fated to slip ever closer to the "rationality horizon", within which the idea ceases to be an interesting hypothesis and becomes an article of faith. At the time, this seemed like a particularly good methaphor for the ascendance of the "black-hole bandwagon" in AGN studies. Indeed, black holes are still an article of faith for most of us, and the question of the day has shifted from "what is the central engine?" to "how does it work?".

The current situation is illustrated below. Instead of falling radially, the unsuspecting theorists are swept into an accretion disk ... they are unaware of the whereabouts of the missing colleagues. Occasionally, one of the observers notices a fleeting "blue bump" on the surface of the disk, another spots an unmistakable profile, but the fragments of evidence don't quite cohere. Before they can reach a comfortable consensus inside the rationality horizon, the theorists are swept away in a poorly collimated, one-sided jet of fog. Some of them interact with the broad line or narrow line region on their way out, and stay at a few parsecs forever; others are expelled from the field entirely.

(taken from pages 412-414 of Begelman)

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