SIMBAD references

We investigate the differences in the M_ø-σ relation derived recently by Ferrarese & Merritt and by Gebhardt and collaborators. The shallower slope found by the latter authors (3.75 vs. 4.8) is due partly to the use of a regression algorithm that ignores measurement errors and partly to the value of the velocity dispersion adopted for a single galaxy, the Milky Way. A steeper relation is shown to provide a better fit to black hole masses derived from reverberation mapping studies. Combining the stellar dynamical, gasdynamical, and reverberation mapping mass estimates, we derive a best-fit relation M_ø=1.30(±0.36)x10⁸ M_☉(σ_c/200 km.s^–1)^4.72(±0.36).