Observational Limits on Type 1 AGN Accretion Rate in COSMOS

• Published in: arXiv.org
• Main Authors: Trump, Jonathan R, Impey, Chris D, Kelly, Brandon C, Martin, Elvis, Merloni, Andrea, Bongiorno, Angela, Gabor, Jared, Heng Hao, McCarthy, Patrick J, Huchra, John P, Brusa, Marcella, Cappelluti, Nico, Koekemoer, Anton, Nagao, Tohru, Salvato, Mara, Scoville, Nick Z
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 07.05.2009
• Subjects: Accretion disks; Active galactic nuclei; Cosmos; Emission; Physics - Cosmology and Nongalactic Astrophysics; Rangefinding; Red shift; Scaling
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.0905.1123

We present black hole masses and accretion rates for 182 Type 1 AGN in COSMOS. We estimate masses using the scaling relations for the broad Hb, MgII, and CIV 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 AGN accrete below L_I/L_Edd ~ 0.01, despite simulations of synthetic spectra which show that the survey is sensitive to such Type 1 AGN. At lower accretion rates the BLR may become obscured, diluted or nonexistent. We find evidence that Type 1 AGN 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 AGN. However the measured range in accretion rate is still comparable to the intrinsic scatter from the scaling relations, suggesting that Type 1 AGN accrete at a narrow range of Eddington ratio, with L_I/L_Edd ~ 0.1.