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Mid-infrared Properties of the Swift Burst Alert Telescope Active Galactic Nuclei Sample of the Local Universe. I. Emission-line Diagnostics

Weaver, K. A. and Meléndez, M. and Mushotzky, R. F. and Kraemer, S. and Engle, K. and Malumuth, E. and Tueller, J. and Markwardt, C. and Berghea, C. T. and Dudik, R. P. and Winter, L. M. and Armus, L. (2010) Mid-infrared Properties of the Swift Burst Alert Telescope Active Galactic Nuclei Sample of the Local Universe. I. Emission-line Diagnostics. Astrophysical Journal, 716 (2). pp. 1151-1165. ISSN 0004-637X.

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We compare mid-infrared emission-line properties from high-resolution Spitzer spectra of a hard X-ray (14-195 keV) selected sample of nearby (z < 0.05) active galactic nuclei (AGNs) detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission lines, [O IV] 25.89 μm, [Ne II] 12.81 μm, [Ne III] 15.56 μm, and [Ne V] 14.32/24.32 μm, and hard X-ray continuum show no differences between Seyfert 1 and Seyfert 2 populations; however, six newly discovered BAT AGNs are under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The overall tightness of the mid-infrared correlations and BAT fluxes and luminosities suggests that the emission lines primarily arise in gas ionized by the AGNs. We also compare the mid-infrared emission lines in the BAT AGNs with those from published studies of ULIRGs, Palomar-Green quasars, star-forming galaxies, and LINERs. We find that the BAT AGN sample falls into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] ratios. These line ratios are lower in sources that have been previously classified in the mid-infrared/optical as AGNs than those found for the BAT AGNs, suggesting that, in our X-ray selected sample, the AGNs represent the main contribution to the observed line emission. These ratios represent a new emission line diagnostic for distinguishing between AGNs and star-forming galaxies.

Item Type:Article
Related URLs:
URLURL TypeDescription
Mushotzky, R. F.0000-0002-7962-5446
Markwardt, C.0000-0001-9803-3879
Armus, L.0000-0003-3498-2973
Additional Information:© 2010 The American Astronomical Society. Received 2009 November 9; accepted 2010 April 29; published 2010 May 27. We thank the referee for very useful comments that improved the paper. We also acknowledge S. Veilleux for valuable comments on the work. This research was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA. L.M.W. acknowledges support under Hubble Fellowship program number HST-HF- 51263.01-A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The IRS was a collaborative venture between Cornell University and Ball Aerospace Corporation funded by NASA through the Jet Propulsion Laboratory and Ames Research Center. SMART was developed by the IRS Team at Cornell University and is available through the Spitzer Science Center at Caltech.
Funding AgencyGrant Number
NASA Postdoctoral ProgramUNSPECIFIED
NASA Hubble FellowshipHST-HF-51263.01-A
Subject Keywords:galaxies: active – galaxies: Seyfert – infrared: galaxies – X-rays: galaxies
Issue or Number:2
Classification Code:PACS: 98.54.Cm; 98.62.Qz; 98.58.Bz; 95.85.Pw; 98.62.Py; 98.70.Lt
Record Number:CaltechAUTHORS:20100628-081343116
Persistent URL:
Official Citation: K. A. Weaver et al 2010 ApJ 716 1151 doi: 10.1088/0004-637X/716/2/1151
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18823
Deposited By: Tony Diaz
Deposited On:02 Jul 2010 03:46
Last Modified:09 Mar 2020 13:19

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