AAS 204th Meeting, June 2004
Session 92 Diagnosing AGN
Oral, Thursday, June 3, 2004, 2:00-3:30pm, 601

## [92.04] Black Hole Mass Estimates for High-Redshift Quasars

M. Dietrich (Georgia State University), F. Hamann (University of Florida)

We investigate a sample of luminous high-redshift quasars (3.3 \leq z \leq 5.1) to measure the mass of their super-massive black holes (SMBH) and compare, for the first time, results based on CIV, MgII, and H\beta emission lines at high-redshifts. Assuming gravitationally bound orbits as dominant broad-line region gas motion, we determine black hole masses in the range of 2 108 \leq Mbh \leq 4 1010 Msun. In spite of some uncertainties, the presence of SMBH at redshifts up to z=5.1 is consistently indicated by all three emission lines. Assuming logarithmic growth by spherical accretion with a mass to energy conversion efficiency of \epsilon = 0.1 and an Eddington ratio Lbol/Ledd calculated for each quasar individually, we estimate black hole growth-times of the order of several ~100 Myr. This result indicates that the SMBHs in the z~q 3.5 quasars began to grow at redshifts z \geq 4, while for the quasars with z\geq 4.5 they started at z ~q 5 to 10. These estimated time scales for forming SMBHs at high-redshifts provide further indications for a joint formation of host galaxies bulges, major and vigorous star formation episodes, and SMBH formation at these early epochs.