MID-INFRARED PROPERTIES OF THE SWIFT BURST ALERT TELESCOPE ACTIVE GALACTIC NUCLEI SAMPLE OF THE LOCAL UNIVERSE. I. EMISSION-LINE DIAGNOSTICS

Journal Article · Sun Jun 20 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/716/2/1151· OSTI ID:21452935

Weaver, K A; Melendez, M; Mushotzky, R F; Kraemer, S; Engle, K; Malumuth, E; Tueller, J; Markwardt, C ^[1]; Berghea, C T; Dudik, R P ^[2]; Winter, L M ^[3]; Armus, L ^[4]

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1. NASA Goddard Space Flight Center, Greenbelt, MD, 20771 (United States)
2. U.S. Naval Observatory, Washington, DC 20392 (United States)
3. Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0440 (United States)
4. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)

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 {mu}m, [Ne II] 12.81 {mu}m, [Ne III] 15.56 {mu}m, and [Ne V] 14.32/24.32 {mu}m, 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.

• OSTI ID: 21452935
• Journal Information: Astrophysical Journal, Vol. 716, Issue 2; Other Information: DOI: 10.1088/0004-637X/716/2/1151; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DUSTS
EMISSION
GALAXY NUCLEI
HARD X RADIATION
KEV RANGE
LUMINOSITY
QUASARS
STARS
TELESCOPES
UNIVERSE
X-RAY GALAXIES
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELECTROMAGNETIC RADIATION
ENERGY RANGE
GALAXIES
IONIZING RADIATIONS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
X RADIATION