Accretion Disks around Black Holes: Twenty Five Years Later

Abstract

Study of accretion processes onto stars began by the works of Hoyle & Lyttleton (1939), almost sixty years ago. They computed the rate at which pressure-less matter would be accreted on a moving star. Subsequently, pressure was included and the spherical flow solution was perfected by Bondi (1952). However, emission from rapidly infalling matter was not found to be strong enough to explain high luminosities of quasars and AGNs. Suggestions to improve the luminosity by magnetic dissipation were then put forth (Shvartsman, 1971; Shapiro, 19 7 3ab). Indeed, efforts to improve luminosity of a spherical flow are on even in recent days (Chang & Ostriker, 1985; Babul, Ostriker & Mészáros, 1989; Nobili, Turolla & Zampieri, 1991). Meanwhile, possible evidence of disklike structures around one of the binary components were found (Kraft, 1963) and some tentative suggestions that matter should accrete in the form of accretion disks were put forward (Burbidge & Prendergast, 1968; Lynden-Bell, 1969). More quantitative studies were made by Shakura (1972). However, the beginning of modern accretion disk physics is traditionally attributed to the two classical articles, one by Shakura & Sunyaev (1973, hereafter referred to as SS73) and the other by Novikov & Thorne (1973, hereafter referred to as NT73), both of which were published exactly twenty five years ago.