A Caltech Library Service

Accretion Rate and the Physical Nature of Unobscured Active Galaxies

Trump, Jonathan R. and Impey, Christopher D. and Kelly, Brandon C. and Civano, Francesca and Gabor, Jared M. and Diamond-Stanic, Aleksandar M. and Merloni, Andrea and Urry, Megan C. and Hao, Heng and Jahnke, Knud and Nagao, Tohru and Taniguchi, Yoshiaki and Koekemoer, Anton M. and Lanzuisi, Giorgio and Liu, Charles and Mainieri, Vincenzo and Salvato, Mara and Scoville, Nick Z. (2011) Accretion Rate and the Physical Nature of Unobscured Active Galaxies. Astrophysical Journal, 733 (1). Art. No. 60. ISSN 0004-637X.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


We show how accretion rate governs the physical properties of a sample of unobscured broad-line, narrow-line, and lineless active galactic nuclei (AGNs). We avoid the systematic errors plaguing previous studies of AGN accretion rates by using accurate intrinsic accretion luminosities (L _(int)) from well-sampled multiwavelength spectral energy distributions from the Cosmic Evolution Survey, and accurate black hole masses derived from virial scaling relations (for broad-line AGNs) or host-AGN relations (for narrow-line and lineless AGNs). In general, broad emission lines are present only at the highest accretion rates (L _(int)/L _(Edd) > 10^(–2)), and these rapidly accreting AGNs are observed as broad-line AGNs or possibly as obscured narrow-line AGNs. Narrow-line and lineless AGNs at lower specific accretion rates (L _(int)/L _(Edd) < 10^(–2)) are unobscured and yet lack a broad-line region. The disappearance of the broad emission lines is caused by an expanding radiatively inefficient accretion flow (RIAF) at the inner radius of the accretion disk. The presence of the RIAF also drives L _(int)/L _(Edd) < 10^(–2) narrow-line and lineless AGNs to have ratios of radio-to-optical/UV emission that are 10 times higher than L _(int)/L _(Edd) > 10^(–2) broad-line AGNs, since the unbound nature of the RIAF means it is easier to form a radio outflow. The IR torus signature also tends to become weaker or disappear from L _(int)/L _(Edd) < 10^(–2) AGNs, although there may be additional mid-IR synchrotron emission associated with the RIAF. Together, these results suggest that specific accretion rate is an important physical "axis" of AGN unification, as described by a simple model.

Item Type:Article
Related URLs:
URLURL TypeDescription
Civano, Francesca0000-0002-2115-1137
Urry, Megan C.0000-0002-0745-9792
Jahnke, Knud0000-0003-3804-2137
Nagao, Tohru0000-0002-7402-5441
Taniguchi, Yoshiaki0000-0003-2247-3741
Koekemoer, Anton M.0000-0002-6610-2048
Lanzuisi, Giorgio0000-0001-9094-0984
Liu, Charles0000-0002-4314-8713
Salvato, Mara0000-0001-7116-9303
Scoville, Nick Z.0000-0002-0438-3323
Additional Information:© 2011 The American Astronomical Society. Received 2010 July 8; accepted 2011 March 2; published 2011 May 5. Based on observations with the XMM-Newton satellite, an ESA science mission with instruments and contributions directly funded by ESA member states and NASA; the Magellan telescope, operated by the Carnegie Observatories; the ESO Very Large Telescope; and the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution; the Subaru Telescope, operated by the National Astronomical Observatory of Japan; and the NASA/ESA Hubble Space Telescope, operated at the Space Telescope Science Institute, which is operated by AURA Inc., under NASA contract NAS 5-26555. J.R.T. acknowledges support from NSF/DDEP grant 0943995, and with C.D.I. acknowledges support from NSF grant AST-0908044. B.C.K. acknowledges support from NASA through Hubble Fellowship grant HF-51243.01, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. Gordon Richards and Pat Hall provided useful comments on the manuscript, and we thank the anonymous referee for thorough suggestions that greatly improved the clarity of this work.
Funding AgencyGrant Number
NASA Hubble FellowshipHF-51243.01
Space Telescope Science InstituteUNSPECIFIED
NASANAS 5-26555
Subject Keywords:accretion, accretion disks; galaxies: active; galaxies: nuclei; galaxies: Seyfert; quasars: emission lines; quasars: general
Issue or Number:1
Classification Code:PACS: 98.54.Cm; 98.62.Mw; 98.62.Qz; 98.62.Js
Record Number:CaltechAUTHORS:20110531-144558191
Persistent URL:
Official Citation:Accretion Rate and the Physical Nature of Unobscured Active Galaxies Jonathan R. Trump, Christopher D. Impey, Brandon C. Kelly, Francesca Civano, Jared M. Gabor, Aleksandar M. Diamond-Stanic, Andrea Merloni, C. Megan Urry, Heng Hao, Knud Jahnke, Tohru Nagao, Yoshi Taniguchi, Anton M. Koekemoer, Giorgio Lanzuisi, Charles Liu, Vincenzo Mainieri, Mara Salvato and Nick Z. Scoville doi: 10.1088/0004-637X/733/1/60
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23844
Deposited By: Ruth Sustaita
Deposited On:31 May 2011 22:50
Last Modified:09 Mar 2020 13:19

Repository Staff Only: item control page