The Black Hole–Bulge Relationship in Quasars

We use QSO emission-line widths to examine the black hole mass - sigmarelationship as a function of redshift and to extend the relationship to largermasses. Supermassive black holes in galactic nuclei are closely related to thebulge of the host galaxy. The mass of the black hole, M_BH, increases with thebulge luminosity and with the velocity dispersion of the bulge stars, sigma_*.An important clue to the origin of this correlation would be an observationaldetermination of the evolution, if any, in the M_BH - sigma_* relationship as afunction of cosmic time. The high luminosity of QSOs affords the potential forstudies at large redshifts. We derive black hole masses from the continuumluminosity and the width of the broad Hbeta line and sigma_* from the width ofthe narrow [O III] lines. We find that radio quiet QSOs conform to theestablished M_BH - sigma_* relationship up to values M_BH of 10 billion solarmasses, with no discernible change in the relationship out to redshifts of $z\approx 3$. These results are consistent with the idea that the growth ofsupermassive black holes and massive bulges occurred simultaneously.Comment: 28 pages, 6 figures, to be published in The Astrophysical Journa