Evolution of the black hole Bulge relationship in QSOs

G. A. Shields (1) , S. Salviander (1) , E. W. Bonning (2)

1 Department of Astronomy, University of Texas
2 LUTH (UMR_8102) - Laboratoire Univers et Théories

QSOs allow study of the evolution of the relationship between black holes in galactic nuclei and their host galaxies. The black hole mass M_BH can be derived from the widths of the broad emission lines, and the stellar velocity dispersion sigma_* of the host galaxy can be inferred from the narrow emission lines. Results based on [O III] and [O II] line widths indicate that the M_BH - sigma_* relationship, at redshifts up to z ≈ 2, is consistent with no evolution or an increase of up to ˜0.5 dex in M_BH at fixed sigma_*. CO line widths offer an estimate of sigma_* for luminous QSOs at high redshifts. The available objects from z ≈ 4-6 have very massive black holes, M_BH ˜ 10 ^9.5M_&sun;, but their CO line widths suggest much smaller host galaxies than would be expected by the local M_BH - sigma_* relationship. The most massive black holes must continue to reside in comparatively modest galaxies today, because their number density inferred from QSO statistics exceeds the present-day abundance of proportionally massive galaxies.

Domaines: Astrophysique [astro-ph]

G. A. Shields, S. Salviander, E. W. Bonning. Evolution of the black hole Bulge relationship in QSOs. New Astronomy Reviews, 2006, 50, pp.809-813. ⟨10.1016/j.newar.2006.06.073⟩. ⟨hal-03742383⟩