2.2. Detection of Massive Black Holes

There has been considerable recent progress in the detection of dark masses, plausibly interpreted as massive black holes, in nearby galactic nuclei (see Ho 1998c and the contribution by S. Faber). A significant fraction of the known black hole candidates, albeit still a small number, in fact are well known LINERs. These include M81 (M_BH 4 x 10⁶ M), M84 (1.5 x 10⁹ M), M87 (3 x 10⁹ M), the ``Sombrero'' galaxy (1 x 10⁹ M), NGC 4261 (5 x 10⁸ M), and Arp 102B (2 x 10⁸ M). Although certainly no statistical conclusions can yet be drawn, these examples nevertheless serve as a powerful proof-of-concept that at least some LINERs are incontrovertibly accretion-powered sources.