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

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[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.

The author(s) of this abstract have provided an email address for comments about the abstract: dietrich@chara.gsu.edu

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