NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-26 T13:54:55 PDT
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For refcode 2005ApJ...628L..29E:
Retrieve 34 NED objects in this reference.
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NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2005ApJ...628L..29E Metallicity Effects on Mid-Infrared Colors and the 8 microns PAH Emission in Galaxies C. W. Engelbracht, K. D. Gordon, G. H. Rieke, M. W. Werner, D. A. Dale, and W. B. Latter Abstract. We examine colors from 3.6 to 24 microns as a function of metallicity (O/H) for a sample of 34 galaxies. The galaxies range over 2 orders of magnitude in metallicity. They display an abrupt shift in the 8 microns - to - 24 microns color for metallicities between one-third and one-fifth of the solar value. The mean 8-to-24 microns flux density ratio below and above 12+log(O/H)=8.2 is 0.08+/-0.04 and 0.70+/-0.53, respectively. We use mid-IR colors and spectroscopy to demonstrate that the shift is primarily due to a decrease in the 8 microns flux density, as opposed to an increase in the 24 microns flux density. This result is most simply interpreted as being due to a weakening at low metallicity of the mid-IR emission bands usually attributed to PAHs (polycyclic aromatic hydrocarbons) relative to the small-grain dust emission. However, existing empirical spectral energy distribution models cannot account for the observed short-wavelength (below 8 microns) colors of the low-metallicity galaxies merely by reducing the strength of the PAH features; some other emission source (e.g., hot dust) is required. Keywords: Galaxies: ISM, Infrared: Galaxies
Retrieve 34 NED objects in this reference.
Please click here for ADS abstract

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