Journal
ASTROPHYSICAL JOURNAL
Volume 700, Issue 1, Pages 49-55Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/700/1/49
Keywords
galaxies: active; quasars: emission lines; quasars: general
Categories
Funding
- NSF ADP [NNX08AJ28G]
- ARCS
- NASA through Hubble Fellowship [HF-01220.01]
- Space Telescope Science Institute
- Association of Universities for Research in Astronomy, Inc., for NASA [NAS 5-26555]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [0908044] Funding Source: National Science Foundation
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We present black hole masses and accretion rates for 182 Type 1 active galactic nuclei (AGNs) in COSMOS. We estimate masses using the scaling relations for the broad H beta, Mg II, and C IV emission lines in the redshift ranges 0.16 < z < 0.88, 1 < z < 2.4, and 2.7 < z < 4.9. We estimate the accretion rate using an Eddington ratio L-I/L-Edd estimated from optical and X-ray data. We find that very few Type 1 AGNs accrete below L-I/L-Edd similar to 0.01, despite simulations of synthetic spectra which show that the survey is sensitive to such Type 1 AGNs. At lower accretion rates the broad-line region may become obscured, diluted, or nonexistent. We find evidence that Type 1 AGNs at higher accretion rates have higher optical luminosities, as more of their emission comes from the cool (optical) accretion disk with respect to shorter wavelengths. We measure a larger range in accretion rate than previous works, suggesting that COSMOS is more efficient at finding low accretion rate Type 1 AGNs. However, the measured range in accretion rate is still comparable to the intrinsic scatter from the scaling relations, suggesting that Type 1 AGNs accrete at a narrow range of Eddington ratio, with L-I/L-Edd similar to 0.1.
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